It uses /usr/share/applications/ /usr/local/share/applications/
Does Nix set $XDG_DATA_DIRS?
I think it doesn't. At least, it didn't set it during my installation.
But it could be set manually.
Furthermore, I don't see this variable set in debian and template VMs. I
don't have "canonical" fedora/debian machines to test it there. If it is
set there, I think qubes should follow the convention. But then, that
variable should also be set in debian/fedora VMs.
What do you think?