The source project of this merge request has been removed.
community/phosh: add config file to specify preferred xdg-desktop-portal
Since phosh is not gnome, xdg-desktop-portal-gnome doesn't work perfectly - some apps do not open the file picker portal. Issue is discussed here in postmarketOS: https://gitlab.com/postmarketOS/pmaports/-/issues/2263
This along with upgrading xdg-desktop-portal itself to v1.17 (merge request: !50105 (merged)) seems to solve the issue on my devices by using the gtk portal instead of the gnome one.