The Republican-led Oversight Committee of the Michigan state Senate has released a report following extensive investigation of the 2020 election in Michigan. They have found "no evidence of widespread or systematic fraud in Michigan’s prosecution of the 2020 election." The report, which is embedded in
this article, is very well done, and it's worth the time to read the whole thing if you're interested in this topic. Among other things, they address (and debunk) many of the specific fraud claims and conspiracy theories about the election.