Closed-source projects have been dealing with this forever, by having a mostly-static pool of employees replenished through job listings and interviews. A FLOSS project adopting this model would certainly feel weird, but could work if there were enough willing candidates. The question is, who will take on effectively a job without the monetary reward?

My understanding is that the people working on ladybird are compensated for their full time positions, so I would also expect any future positions to be similar.

This is needed for more projects than just ladybird, and I'm sure will be worked out.

For now this makes sense.

Maybe it is, if they can somehow vet potential new contributors in-person at e.g. conferences.