I apologize but I don’t understand this metric - you’re saying Trump would have gotten the majority if republicans who didn’t vote for him had voted for him ? That’s some serious squinting and if you do that I’ll just take everyone who voted for Biden in the primary and add it to Harris and now she won close to 70% of the votes? Maybe add in Obama’s last election results and every democrat that ever ran in any races and Trump then got about 0% of the votes.
Sadly you can only count the votes the candidate who ran actually received. And he had a plurality - the weakest of all possible victories other than his victory of Clinton where she had more votes than him and still lost on an arcana.