DBus-enabled applications installed from Flatpak won't open

If you open a Flatpak application with DBusActivatable=true in the .desktop file (mostly GNOME applications), the applications will not open on OpenRC images. It will open if you open with flatpak run, but opening with gapplication results in the following error:

luna@xenia ~ $ gapplication launch org.gnome.Loupe
error sending Activate message to application: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.Loupe was not provided by any .service files

This appears to be resulting from DBus not seeing /var/lib/flatpak/exports as a valid location to find DBus service files.

As a temporary workaround, running ln -sf /var/lib/flatpak/exports/share/dbus-1/ /home/$USER/.local/share/ will work.

To fix this, we need to find how to configure DBus to see this path.