A lot of evidence that biased polls are being commissioned in battleground states by Republican groups showing Trump winning.

Yes. This is what's behind Trump's "surge." However, the legitimate poll aggregators exclude the partisan pollsters because they add nothing meaningful to the average. It seems counter-intuitive - if the biased polls make it look like Trump is doing better than he actually is, that might lead some Republican voters to stay home because it's not necessary to vote if he's going to win anyway. But using these polls as "proof" that the election was "stolen" is probably the idea. The problem is that there will be exit polls which will be much more accurate. Of course, the real battle won't be in court, but in the minds of the MAGA crowd.