linux save file location

[vegan cookies]

Running arch linux using proton to play the game, wanted to back my save up as I just completed paramedic (also now ready to scream):
[tom@Arch-Tom GTA3 User Files]$ pwd
/home/tom/.var/app/com.valvesoftware.Steam/.local/share/Steam/steamapps/compatdata/12100/pfx/drive_c/users/steamuser/Documents/GTA3 User Files

Appears to have my safe folders.

If this isn't the case for you would recommend searching for the folder name:
"GTA3 User Files"