Well, you can round down everything short of outright civil war to 'zero' but then you might miss important signals that you could act on. That doomsday message so far seems to be largely on the money, and in some ways has already been exceeded. That doesn't mean it can't get much worse.
The old guard of nonfascist Republicans wasn't purged until late in the last Trump term and into the period between Trump terms, and was particularly strong in the first half of the last term, the second half of last term, the Democrats controlled the House, limiting. There was not a trifecta under a fully Trump-aligned Republican Party until the current term. That makes a difference in outcomes, and has already made obvious differences in outcomes in exactly the direction discussed.
But — unlike the attempted coup which was totally his fault — I'm not sure you can blame even half of that death toll on Trump, given all the other countries that also did badly.
I can blame Trump for his policy and also his and the larger Republicans parties ideological brigade against medicine and science. Which still continues to this day, and will continue to take lives.
I'm not above blaming extremely powerful people for harmful abstract ideology. I'll do it.
Sure, and I do too, but the relative difference between "ideological brigade against medicine and science" and "what the various Europen countries did" suggests that the difference between Trump as he was and a plausible competent alternative still didn't add up to 5e5 lives per 342 million population.
China, I think, managed to get their response right (eventually, having failed hard right at the start). Either that or they managed to hide the death toll in several different dependent outputs that all roughly agree with these numbers: https://en.wikipedia.org/wiki/COVID-19_pandemic_by_country_a...
(That said, this map also says that the USA should be ruled over by Canada, with King Charles as head of state etc., I absolutely do not disagree that a lot of dumb things were done and should've played out differently, this is just a relative statement about how incredibly mediocre a lot of our other leaders besides Trump are in the supposedly developed nations…)