Собственно, сабж: https://www.phoronix.com/news/systemd-appd-Flatpak-Dev .
Sebastian Wick and Adrian Vovk are planning to develop «systemd-appd» as a new service to allow querying running app instances. The plans for systemd-appd are for being able to authenticate Flatpak instances and working towards a goal of supporting nested sandboxing. This will also be useful for work around PipeWire, eliminating the D-Bus proxy, and other modernization work.
