OK. Fix worked, but it lost all my settings from before.
Looks like I need to look up how to reconnect to my NVME drive.
Edit: Followed previous advice and have a working system again. Still wish I could install all the updates except the wonky kernel. (Handy advice: Boot Failure A311D Restoring Connection to Encrypted NVME - #21 by josch)
Edit: regular upgrade added 6.12.6 kernel and all is well!