GNOME is not necessary. Portals probably are not either, but the NixOS module requires them. Not sure why it did not work without GNOME before.
Along with the `socat` fix in the parent commit, this makes the Flatpak’s installed tests finally pass again. The tests seem to need slightly over 2G of disk space, and it appears that the test suite was ported to Python 3 in 1.5.1: 2b6641575d
2b6641575d
optionalPackages are deprecated.
The test script is also ported to python.