The face is from the “it’s free real estate” meme, with the unspoken words being the punchline

I did a search for nvidia on my system and got these, which OP might wanna check for too:

egl-wayland
lib32-nvidia-utils
libvdpau
libxnvctrl
nvidia-open
nvidia-settings
nvidia-utils
opencl-nvidia 

I’ve installed extra packages for proton and machine learning, so some of these may not be there, but hopefully that helps.

Well your /efi entry looks right to me - maybe try mount -a (maybe capital A, going off memory here but whichever option is all) and watch for error messages or check dmesg?

sdb looks like the bootable USB to me - /dev/sda1 should be the system’s EFI, no? OP, could you try mounting that one (shouldn’t be encrypted afaik) and/or post the output of cat /etc/fstab? Edit: just realized you were unable to mount the encrypted drive in the first place so /etc is inaccessible, sorry

I ran it (bg3.exe) through the latest vanilla proton (9.0.1 I think?) earlier today and it had no issues. I used the experimental version for character creation and it had some fucked up textures (color banding mostly), but after switching it ran perfectly in the stable version. I’m running thru steam on a nvidia gpu, so hopefully on amd you’ll be fine if you try that.