tldr: Trump and others filed 62 lawsuits claiming election fraud in the 2020 election, and so far none have ruled in his favor. In fact, the electronic voting systems have filed defamation suits against his team and others making claims of election fraud. This all seems to suggest that the 2020 election was at least fair in terms of voting process.
Quotes from Wikipedia:
"After the
2020 United States presidential election, the
campaign for incumbent President Donald Trump and others filed 62 lawsuits contesting election processes, vote counting, and the vote certification process in 9 states... Nearly all the suits were dismissed or dropped due to lack of evidence or lack of standing, including 30 lawsuits that were dismissed by the judge after a hearing on the
merits. Among the judges who dismissed the lawsuits were some appointed by Trump himself."
"Only one ruling was initially in Trump's favor: the timing within which first-time Pennsylvania voters must provide proper identification if they wanted to “cure” their ballots. This ruling affected very few votes, and it was later overturned by the
Pennsylvania Supreme Court."
"
Dominion Voting Systems brought defamation lawsuits against former Trump campaign lawyers
Sidney Powell and
Rudy Giuliani, each for $1.3 billion.
Smartmatic brought a defamation lawsuit against
Fox Corporation and its anchors
Lou Dobbs,
Maria Bartiromo, and
Jeanine Pirro as well as Giuliani and Powell for $2.7 billion." <The fact that they brought defamation suits means they opened themselves up to discovery, which seems to indicate they had nothing to hide.