> Blink and you’ll get a different measurement.
This means your environment is not controlled enough. Also quality control is usually done in terms of statistics. You might want to read something called gauge R&R. That being said, you should be proud of being able to ship a physical product!
As for quality checks, software quality teams pales in comparison to hardware quality teams. Mainly as you said, there’s a lot checks you can do in software. For hardware, bigger companies have to have their vendors qualified. The vendors have to follow their customer guidelines and do outgoing inspection. Then the company has a division to do incoming inspection. There’s a traveler that follows the kit (of parts) and there’s usually subassembly quality checks. Then final full build checks before it leaves the door.