The number of 'Independent' Congresspersons today is infinitesimal and I believe they all caucus with the Democrats. What would Trump running as an Independent accomplish? I highly doubt that he could win running as such. Why? Because there are no MAGA Democrats who would vote for him and I'd bet that the republican MAGA camp would split between Trump the Independent and the Republican candidate.
IMHO - the only path for MAGA to dictate its agenda is to take over the Republican party.
Remember Ross Perot? Me, either.
The biggest victory of that other selfish independent party bid was 1 Gov race win, in MN.
Jesse "The NoBody" Ventura.
I don't wish that fate on Trump.
Running as a Democrat could accomplish this even better. If he can hold MAGA across party lines that could work. Especially if he can get Manchin to run. If Biden doesn’t go then there will be a major primary and he could win on vote splitting shenanigans. Who knows
And that's true for any political groups, including libertarians, etc.. if you don't have enough support to gain control of a party, you're certainly not going to have enough to win a general election.