I can not reply your whole questions, however I may give you some assist.

From the bitcoin standpoint, you possibly can all the time spend a transaction output (TXO) if it isn’t spent already by some confirmed transaction.
That stated, in the event you opened a channel however the funding transaction is just not confirmed you possibly can spend the TXO that funded the channel, however I do not know the way lightningd would react to this.

You stated you will have closed the channel. When you funds are nonetheless caught it means each the funding channel and shut channel transactions are unconfirmed within the mempool.

I’d attempt to spend the TXO within the shut TX in a child-pays-for-parent style. Nonetheless, when attempting to breed that situation in regtest I discover troubles with the clightning consumer interface.

I did the next to simulate your scenario:

1. I create a channel with peer

$ l1-cli fundchannel 0397d48baf82cf731fc8967c16e3d9575f10606bdf481738eb9cafeda29d0e3d67 1000000sat
{
   "tx": "02000000000101ee026cb7c44f482eb9b1e11f6faf11956ac26f4cdb7e0c1aa9ef94025ec412c30000000000fdffffff0240420f000000000022002075e9a102dbb348646e2f1804cc3cfec9edb6f5551a074f33a615f29cbd45eeaa4c5bd70500000000160014deb1f4e1123694ca3e418cefe496d3c26b0ddde202473044022068b402d53f16204324b28607eca046a4f7121d8f83c62e17de9c9131e307b5cf022077a3aa538469f9e0983cce98c3de4c5427731b398ed395d9614cf7b54d4f5cdd012102f5093f8fd66c909fc72ee556e70cb038ae92b03fd1b56d710cf53b3cc019868e73000000",
   "txid": "11b8967c62c584da9bbba5243d61bc95b4da210760bca04adb7c349319edba19",
   "channel_id": "9dfe0df4c502c31e92c266bfa28af18d6f6d11a0b0197b838797f8c990625168",
   "outnum": 0
}

2. I closed the channel

$ l1-cli -k shut id=9dfe0df4c502c31e92c266bfa28af18d6f6d11a0b0197b838797f8c990625168 
# Sending closing payment provide 139sat, with vary 139sat-183sat
# Acquired closing payment provide 139sat, with vary 139sat-1000000sat
{
   "tx": "020000000119baed1993347cdb4aa0bc600721dab495bc613d24a5bb9bda84c5627c96b8110000000000ffffffff01b5410f00000000001600141b420a80810dda8fd3621e6ba4ce14ce85b6877e00000000",
   "txid": "e6a7d6cc0960f0f7481a3e9a18b9d9cc18ee695dd626a597883be4599c043699",
   "sort": "mutual"
}

At this level each the funding (11b896...) and settlement (e6a7d6cc...) transactions are within the mempool and unconfirmed.
The scenario is proven within the diagram beneath

tx:c312c...(confirmed) ---> tx:11b89... (funding tx unconfirmed) ---> tx:e6a7d6cc... (settlement, unconfirmed)

My thought is to spend the settlement output with a better payment.
Nonetheless, I’ve issues with lightning-cli to get this working.

If I attempt to spend the settlement output, which is managed by my pockets:

$ l1-cli -k txprepare outputs="[{"bcrt1qx77wq9fyxvhsncswpl6kgqpnc49m5e5lzmls0g":"all"}]" utxos="["e6a7d6cc0960f0f7481a3e9a18b9d9cc18ee695dd626a597883be4599c043699:0"]" feerate=100
{
   "code": -32602,
   "message": "Unknown UTXO e6a7d6cc0960f0f7481a3e9a18b9d9cc18ee695dd626a597883be4599c043699:0"
}

So in all probability lightnind is saying: “that UTXO is just not within the blockchain, I can not spend it”.

I attempted a work-around, making a PSBT with bitcoin-cli:

$ bt-cli createpsbt "[{"txid":"e6a7d6cc0960f0f7481a3e9a18b9d9cc18ee695dd626a597883be4599c043699","vout":0}]" "[{"bcrt1qx77wq9fyxvhsncswpl6kgqpnc49m5e5lzmls0g":0.00900000}]"
cHNidP8BAFICAAAAAZk2BJxZ5DuIl6Um1l1p7hjM2bkYmj4aSPfwYAnM1qfmAAAAAAD9////AaC7DQAAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAAA

after which signing it with lightning-cli:

$ l1-cli signpsbt cHNidP8BAFICAAAAAZk2BJxZ5DuIl6Um1l1p7hjM2bkYmj4aSPfwYAnM1qfmAAAAAAD9////AaC7DQAAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAAA
{
   "code": -1,
   "message": "No pockets inputs to signal"
}

It appears that evidently clightning does not prefer to signal transactions inputs that aren’t confirmed.

I’d spend the TXO that funded the channel because the funding transaction is unconfirmed.

$ l1-cli -k txprepare outputs="[{"bcrt1qx77wq9fyxvhsncswpl6kgqpnc49m5e5lzmls0g":"all"}]" utxos="["c312c45e0294efa91a0c7edb4c6fc26a9511af6f1fe1b1b92e484fc4b76c02ee:0"]" feerate=100
{
   "code": -32602,
   "message": "UTXO c312c45e0294efa91a0c7edb4c6fc26a9511af6f1fe1b1b92e484fc4b76c02ee:0 already reserved"
}

So, clightning sees that despite the fact that that TXO is just not confirmed it’s spent by a channel funding.

Let me strive forcing once more with bitcoin core PSBT:

$ bt-cli createpsbt "[{"txid":"c312c45e0294efa91a0c7edb4c6fc26a9511af6f1fe1b1b92e484fc4b76c02ee","vout":0}]" "[{"bcrt1qx77wq9fyxvhsncswpl6kgqpnc49m5e5lzmls0g":0.98900000}]"
cHNidP8BAFICAAAAAe4CbLfET0guubHhH2+vEZVqwm9M234MGqnvlAJexBLDAAAAAAD9////ASAY5QUAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAAA

after which get a signature from clightning pockets:

$  l1-cli signpsbt cHNidP8BAFICAAAAAe4CbLfET0guubHhH2+vEZVqwm9M234MGqnvlAJexBLDAAAAAAD9////ASAY5QUAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAAA
{
   "signed_psbt": "cHNidP8BAFICAAAAAe4CbLfET0guubHhH2+vEZVqwm9M234MGqnvlAJexBLDAAAAAAD9////ASAY5QUAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAEBHyae5gUAAAAAFgAUrxY3yj79dai67Z9mJ4hHAjQSIzMiAgL1CT+P1myQn8cu5VbnDLA4rpKwP9G1bXEM9Ts8wBmGjkcwRAIgMdOln+3Bzrm5lWqUrBbtEleqYgclYdwSadbs7T8V+18CIFTRsrlwhdZrvrG+UiCGf44+TJrF+Oqj4w+hLFmucBcfASIGAvUJP4/WbJCfxy7lVucMsDiukrA/0bVtcQz1OzzAGYaOCK8WN8oAAAAAACICAoqr3sVLia14vPyrtYQRxA+wniCHWDV34AMh8C5p18haCDe84BUHAAAAAA=="
}

OK, so this time we’ve got a signature, now we will assemble the transaction

$ bt-cli finalizepsbt "cHNidP8BAFICAAAAAe4CbLfET0guubHhH2+vEZVqwm9M234MGqnvlAJexBLDAAAAAAD9////ASAY5QUAAAAAFgAUN7zgFSQzLwniDg/1ZAAzxUu6Zp8AAAAAAAEBHyae5gUAAAAAFgAUrxY3yj79dai67Z9mJ4hHAjQSIzMiAgL1CT+P1myQn8cu5VbnDLA4rpKwP9G1bXEM9Ts8wBmGjkcwRAIgMdOln+3Bzrm5lWqUrBbtEleqYgclYdwSadbs7T8V+18CIFTRsrlwhdZrvrG+UiCGf44+TJrF+Oqj4w+hLFmucBcfASIGAvUJP4/WbJCfxy7lVucMsDiukrA/0bVtcQz1OzzAGYaOCK8WN8oAAAAAACICAoqr3sVLia14vPyrtYQRxA+wniCHWDV34AMh8C5p18haCDe84BUHAAAAAA=="
{
  "hex": "02000000000101ee026cb7c44f482eb9b1e11f6faf11956ac26f4cdb7e0c1aa9ef94025ec412c30000000000fdffffff012018e5050000000016001437bce01524332f09e20e0ff5640033c54bba669f02473044022031d3a59fedc1ceb9b9956a94ac16ed1257aa62072561dc1269d6eced3f15fb5f022054d1b2b97085d66bbeb1be5220867f8e3e4c9ac5f8eaa3e30fa12c59ae70171f012102f5093f8fd66c909fc72ee556e70cb038ae92b03fd1b56d710cf53b3cc019868e00000000",
  "full": true
}

and broadcast it

$ bt-cli sendrawtransaction 02000000000101ee026cb7c44f482eb9b1e11f6faf11956ac26f4cdb7e0c1aa9ef94025ec412c30000000000fdffffff012018e5050000000016001437bce01524332f09e20e0ff5640033c54bba669f02473044022031d3a59fedc1ceb9b9956a94ac16ed1257aa62072561dc1269d6eced3f15fb5f022054d1b2b97085d66bbeb1be5220867f8e3e4c9ac5f8eaa3e30fa12c59ae70171f012102f5093f8fd66c909fc72ee556e70cb038ae92b03fd1b56d710cf53b3cc019868e00000000
41304c4e992a0718d29cf7c46adb0f361c319d31b92eeb8d7dbc811aebc2b39f

If the miners embrace the final transaction 41304..., then the funding 11b896... and settlement e6a7... will likely be invalid. However you continue to have your funds.

tx:c312c...(confirmed) -X-> tx:11b89... (funding tx unconfirmed) -X-> tx:e6a7d6cc... (settlement, unconfirmed)
|
+---> tx:41304... (confirmed)

Unwanted side effects

clightning sees the brand new funds, however it’s nonetheless ready for the earlier transactions to substantiate:

$ l1-cli listfunds
{
   "outputs": [
      {
         "txid": "11b8967c62c584da9bbba5243d61bc95b4da210760bca04adb7c349319edba19",
         "output": 1,
         "amount_msat": 97999692000,
         "scriptpubkey": "0014deb1f4e1123694ca3e418cefe496d3c26b0ddde2",
         "address": "bcrt1qm6clfcgjx62v50jp3nh7f9kncf4smh0z2v5q3d",
         "status": "unconfirmed",
         "reserved": false
      },
      {
         "txid": "41304c4e992a0718d29cf7c46adb0f361c319d31b92eeb8d7dbc811aebc2b39f",
         "output": 0,
         "amount_msat": 98900000000,
         "scriptpubkey": "001437bce01524332f09e20e0ff5640033c54bba669f",
         "address": "bcrt1qx77wq9fyxvhsncswpl6kgqpnc49m5e5lzmls0g",
         "status": "confirmed",
         "blockheight": 116,
         "reserved": false
      }
   ],
   "channels": [
      {
         "peer_id": "0232a73b00b1e4eb6ee1787785640dca55a67bf5e6b338e42efff6a9b21da26c93",
         "connected": true,
         "state": "CHANNELD_NORMAL",
         "channel_id": "a8664ad1bbc4debd16ea2a49b07167f35d3dd9cacac60c0ad6d60fbb76ce78e7",
         "short_channel_id": "103x1x1",
         "our_amount_msat": 1000000000,
         "amount_msat": 1000000000,
         "funding_txid": "c312c45e0294efa91a0c7edb4c6fc26a9511af6f1fe1b1b92e484fc4b76c02ee",
         "funding_output": 1
      }
   ]
}