xdg-desktop-portal is like half broken

[fyrk]

The fix for #348 in fd00de202cc0287f7b34c237b8585e67fe7b85f7 seems to break XDG Portals from within Flatpak on my machine. For example, clicking on a link inside a Flatpak app or opening an attachment in Evolution installed as Flatpak no longer works.

This can be reproduced by running xdg-open from within a Flatpak sandox:

➜ flatpak run --command=sh org.signal.Signal # any flatpak id
[📦 org.signal.Signal ~]$ xdg-open https://example.com/

which will produce the following Journal:

Sep 17 15:46:55 unicornix systemd[3344]: Started app-flatpak-org.mozilla.firefox-169217.scope.
Sep 17 15:46:55 unicornix org.mozilla.firefox.desktop[169228]: Error: no DISPLAY environment variable specified

It works if I re-add

systemd.user.services.niri-flake-polkit = {
  after = [ "graphical-session.target" ];
};

to my config.