Not sure he achieved that much with North Korea other than give Kim Jong-Un some photo opportunities. The Abraham Accords are, or could be, more interesting, although it's not clear how it "deals with Palestine" so much as isolates Iran, which is probably the real aim.
Most people would give Trump the China credit, although even there t's clear that he woefully misunderstood the effects of his own trade war, and consistently misrepresented the meaning of tariffs.
Moreover, as I've pointed out elsewhere, Trump failed in several ways on his domestic policy: on his three main 2016 priorities, he achieved only one, failed on a second, and never even seemed to bother with the third. Even the tax reform achievement was a benefit primarily for the wealthy, and has potentially some nasty stings in the tail coming over the next few years. And that's even before we consider his disastrous approach to Covid.
The simple fact is that Trump has been in this for himself, and his family, and never in it for America. This explains his attitude to the result: Trump's image is built around winning, and therefore he cannot be seen to have lost legitimately. But his fight is destroying America's image, undermining its attempt to promote democracy around the world, and serves to undermine the smooth transition of power.