Yeah I think that's true. From my experience it's the same for testing software in general - you can mock things but having actual tests that test the behaviour of dependencies is tricky since you have to emulate those for your tests and that can be a lot of work.
But since it covers your for all future changes, it might still be worth it, because otherwise you either have to manually retest with actual hardware or accept a higher risk of bugs.
But since it covers your for all future changes, it might still be worth it, because otherwise you either have to manually retest with actual hardware or accept a higher risk of bugs.