There are case reports of people achieving remarkable rehabilitation by stressing their bones and muscles with weight lifting, for example: https://startingstrength.com/article/barbell_training_as_reh...
In general the theory I usually see now is that rehabilitation is best achieved by putting pain-free stress on the thing being healed, with some arguing for low levels of pain in some circumstances.
In my experience you do have to tolerate pain for things like range of motion/stretching. My ankle wouldnt have near the range of motion it has now after breaking it if I wasn't pushing into a decent amount of pain to stretch it.
I fractured my greater trocahnter (not sure if this is the proper english name) in a bike crash 2 years ago. My doctor, seeing the MRI told me I need an operation asap. None of the hospitals that he sent me to (including a sports clinic) wanted to operate it, and just told me to let it heal, with check-ups every 4 weeks. Another doctor in another country told me to get the operation, stay in bed 3 months and get blood thinners. 1 month after the accident I couldn’t take it to stay at home and stand still so I started walking again quite a lot and started weight lifting (upper body and trying to not stress the hip too much). 4 months later you couldn’t even notice that I had the accident, no limping, could start running again, fracture was fully “welded” on its own.