It adds FD support to the device provider so apps like #cheese can just pass in the FD from the portal and get a list of available cameras, which then use the same FD/pipewire connection.
It should get released in Pipewire 0.3.64 pretty soon.
Now I just need to figure out how to get an up-to-date version of Pipewire into the gnome-nightly runtime :)
https://gitlab.freedesktop.org/pipewire/pipewire/-/merge_requests/1475