Not to burst anyone's bubble, but I fixed the locations of the user ROMs and also fixed the "include paths" for those ROMs
The old code would first check $prefix/share/vice and then dirs related to the binary and then finally some user dir. (~/.vice or ~/.config/vice were both wrong)
So now the order is*: ~/.local/share/vice, dir_of_the_binary (mostly for Windows), $prefix/share/vice.
* = vice will read XDG env variables so VICE is compatible with flatpak/snap. compile with --enable-debug-gtk3ui to have VICE spit out the final search path.