I maybe misunderstanding this, but it seems like you're not really concerned about whether or not she's laying eggs for you to eat, but more concerned with her health as a result of not leaving the nest box.
My chicks are only only 7 weeks old so I haven't had to deal with this myself, but from what I read here it seems like the thing to do would be make the nest box(es) uncomfortable for her to sit in for a few days until she's over being broody.
Since you don't have the space to setup a broody jail something like this might work:
https://a.co/d/7On4ni0 to my understanding she won't lay eggs if she'd broody anyway, so making the nest box uninviting to lay in wouldn't really hurt. They can still sleep and roost in the coop at night.
As stated I haven't dealt with this myself, so wait for others to weigh in on the idea.