The point that really bears repeating here is that much of the credit given to Trump for his accomplishments went to things that were too easily reversed, and that is largely due to Trump's own habit of alienating anyone who isn't 100% loyal to him.
We should have neutered Obamacare, but Trump had gone out of his way to offend the easily offended John McCain, who retaliated by killing Obamacare reform just to deprive Trump of a victory.
He didn't get through anything on the border except emergency funding that wasn't sufficient, and that was started too late into his Presidency to be completed anyway. What's sad about that is that it appears two Republican governors who started shipping illegals up north to sanctuary cities may have had a lot more success shifting the debate on illegal immigration than Trump ever did as President.
Other than the tax bill - which got written by Ryan and rammed through by the despised Ryan and McConnell - the rest was just EO's, easily reversed by Biden. That's why it shouldn't be a shock to see the damage Biden has been able to do barely two years into his presidency.
The other part of Trump's legacy that shouldn't be overlooked is giving us a Democrat House in 2018, which pretty much ended any chance of legislative accomplishments in the second half of his term.
The guy is the anti-coalition builder because everything is "Me v. The World", and without the ability to build legislative coalitions, he'd get even less done in a second term than he did in the first...unless he slides left, decides to increase spending, and can grab a bunch of Democrat votes that way to create his "legacy".
As for offending McCain, Trump's presence in the White House offended McCain, who thought it should have been him. Envy is not the foundation of coalitions. Admittedly, Trump makes unforced errors of hostility, forgetting, or perhaps never having learned that you don't make an enemy unnecessarily.
But there was the whole "Country Club" GOP who were hostile in a passive aggressive way to Trump, and who practically mandated him using EOs to get anything done. I can't say that crowd was hostile to the open border (still aren't exactly up in arms about it) or Obamacare, and THAT'S why they are still around. Had the House and Senate pounced on those issues day one of Trump's term, that would have been taken care of, but that was not forthcoming,for whatever reason. It would have cost Congressional campaigns more fodder for the stump,
promising to do something about those issues, which was easy, but nothing meaningful has been done since Eisenhower, except to put up enough wall to reroute the less athletic invaders.