Search 'laser goniometer' on the web.
These devices have been around a while, and some are pretty sophisticated & PRICEY. As for perfect & precise accuracy, I think they're still somewhat limited. But organizations like CATRA rely upon them for some pretty sophisticated testing of edge geometry vs. edge retention and sharpness.
Due to price of the good ones, maybe not 'practical' for hobbyists. But definitely not 'gimmicky', in that they can be useful instruments in knowledgeable hands.