Loader not using Desktop Portals picker on NixOS

[WhiteHusky]

Context in Discord.

As far as I'm told, Avalonia switched over to using dbus (which I'm assuming is XDG Desktop Portals) and it should be spawning the DE's picker. But it isn't and instead falls back to using the GTK3 picker.

However if the Client is started within a dev environment the Desktop Portals picker appears.

So package.nix needs a look at and I'm stumped at the moment even after giving it dbus in the runtime dependency.

[WhiteHusky]

dbus messages with Loader

method call time=1761112917.367053 sender=:1.2034 -> destination=org.freedesktop.DBus serial=1 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=Hello
method return time=1761112917.367065 sender=org.freedesktop.DBus -> destination=:1.2034 serial=1 reply_serial=1
   string ":1.2034"
signal time=1761112917.367074 sender=org.freedesktop.DBus -> destination=(null destination) serial=2907 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameOwnerChanged
   string ":1.2034"
   string ""
   string ":1.2034"
signal time=1761112917.367091 sender=org.freedesktop.DBus -> destination=:1.2034 serial=2 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameAcquired
   string ":1.2034"
method call time=1761112917.411054 sender=:1.2034 -> destination=org.freedesktop.DBus serial=2 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=AddMatch
   string "type='signal',sender='org.freedesktop.DBus',interface='org.freedesktop.DBus',member='NameOwnerChanged',path='/org/freedesktop/DBus',arg0='org.freedesktop.portal.Documents'"
method return time=1761112917.411073 sender=org.freedesktop.DBus -> destination=:1.2034 serial=3 reply_serial=2
method call time=1761112917.411079 sender=:1.2034 -> destination=org.freedesktop.DBus serial=3 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=GetNameOwner
   string "org.freedesktop.portal.Documents"
method return time=1761112917.411088 sender=org.freedesktop.DBus -> destination=:1.2034 serial=4 reply_serial=3
   string ":1.10"

dbus messages with dev Client

method call time=1761113093.706524 sender=:1.2046 -> destination=org.freedesktop.portal.Desktop serial=5 path=/org/freedesktop/portal/desktop; interface=org.freedesktop.DBus.Introspectable; member=Introspect
method return time=1761113093.707148 sender=:1.8 -> destination=:1.2046 serial=7526 reply_serial=5
   string "<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
[Successful Desktop Portal exchange...]