I ran Lineage on my OnePlus 5 for a few years until I replaced it with a Pixel 8 last month. The first thing I did with it was install GrapheneOS. I have not had any issues so far.
Do you have an earlier snapshot that you can roll back to? If not then this is a learning experience about how you should take a snapshot before doing any configuration changes/updates. And also maybe some automatic ones on a schedule (daily/weekly).
As far as recovering files, you could try the Windows recovery environment (or whatever they call it). Take a snapshot first, in case it makes things worse.