But is there anything to stop reverse engineering the physical printer itself, improving on it by 10mm build volume in each direction, and releasing that?
It won't be a copy of the Bambu printer AND it can run the same software, truly freely.
Or do you mean manufacturing your own printer that is a copy of theirs with 10mm extra build volume in each direction, and with your own software? That may be illegal if they have any patents, but otherwise should probably be ok, and would of course not have anything to do with their software - but you still couldn't take the software from one of their printers and running it on yours, most likely.
It just seems like they don't have that much of a moat which is why they are guarding the software bit as much as they can.