Depends on what you mean by "all Ubiquiti devices". My Unifi APs, switches, and EdgeRouter don't need to phone home and the controller can be run (intermittently if desired) on your laptop or a VM. My parents have an all-Ubiquiti network and the only time they have a controller in their house is when I come visit and do an upgrade.
My network has an always-on Ubuntu VM hosting the controller, but it's not needed for normal operation here either. (It is needed for things like guest portal pages and some network stats tracking.)
I just tested my local admin login and it still works. (Now, can I guarantee that nothing has even called-home and told Ubiquiti about that? Of course not.)
Cameras are a different ballgame; Ubiquiti cameras are much more tied to their software and hardware (and thus I don't have any).