The metal score is fairly disappointing. I think however that the architectures of the M1 and a 3080 are so different that synthetic benchmarks are not incredibly useful. At the same time non-synthetic benchmarks are far more likely to be better optimised for NVIDIA cards / Windows, so...
It feels like trying to say whether or not a Tesla is as fast as a Porsche 911. In some respects it is, but in other respects it definitely isn't.
Then again Apple brought this on themselves by comparing the M1 to a 3080, and if the metal score truly is only 68k then that was probably a mistake.