Anecdotally, I saw some folks on reddit's linux board that were running Linux in virtual machines on the M1 and getting quite decent results.
Given that the individual cores benchmark at the very high end of any core available today, this is almost certainly not significant.
If another OS doesn’t take advantage of the specialized processors, it will run slower, but only on specialized loads.
Point is that if you try to run a different OS, it will likely run slower, perhaps significantly slower than running macOS