User-specified portal definitions

[Jaakkonen]

Is it currently possible to have a user-specified .portal definition?

Based on the source code the code loading the portal definitions only looks at the {DATADIR}/xdg-desktop-portal/portals or XDG_DESKTOP_PORTAL_DIR but with no option for looking at ~/.local/share/... and the main system configs.
load_installed_portals
Specifying user overrides is for configuration seems to be possible though in load_portal_configuration

My intent is to use org.freedesktop.impl.portal.FileChooser provided by org.gnome.Nautilus and to write a .portal definition for pointing its existence out. Currently this seems achievable only by writing my own portal that just proxies the DBus calls but even that would need administrator privileges to set up since the portal description would need to be in /usr/lib/xdg-desktop-portal/portals/myportal.portal. The xdg-desktop-portal-gnome forwards the calls to Nautilus like this but doesn't work outside of Gnome (while I'm using Sway).

[Jaakkonen]

It seems that this possibility is coming in #1665