but what if I’m working on something meaningful?

I can’t MVP my way to a simulation physics engine, when each feature or partial feature requires weeks of planning, testing, iterating and tweaking- privately, before anything can be delivered to be used.

Feedback, implies a working widget.

Feedback does not need to be on a MVP, it can be given before that from your fellow engineers. That said there are tasks which really take a lot of research before even fellow engineers can give feedback.