I can't speak for polkit, but in the absence of rtkit the gid/uid limits set in limits.conf work just fine even over a portal. I honestly never understood what

I can't speak for polkit, but in the absence of rtkit the gid/uid limits set in limits.conf work just fine even over a portal. I honestly never understood what was allegedly gained by moving that logic from one place to another. (For that matter the analogy with polkit and group permissions works for a lot of things.)