'Trump does believe in the rule of law' - what on earth are you basing that on? Trump doesn't believe in anything except Trump. He did, as it turns out, happen to select Supreme Court Justices who are rather better and more credible than the existing ones Alito and Thomas (I'm becoming quite a fan of Coney Barrett), but I'm pretty sure that's more Leonard Leo's achievement than his. Anyhow, back to immigration - I discussed this in much more detail with Tom above as you may have seen, but long story short, I don't buy that the difference between both presidents' policies has been as extreme as you imply. At the end of the day, if record numbers of people are stopped at the border, they are still getting stopped - and no, the number of illegal immigrants now isn't significantly higher than it has been for most of the past 20 or 25 years. As a percentage of the total population, it's smaller.
Moreover, both in the US and in Europe, both legal and illegal immigrants are often not stealing jobs from locals, but rather doing jobs for which employers simply can't find any local workers. Or not at wages that they can afford without their businesses going bankrupt, anyway - because it's all good and well to want higher wages for low-skilled workers, but if at the same time you are adamant about leaving big companies entirely free to do whatever they want with their money, including just handing it out to their shareholders or buying back shares and always trying to increase their profits further and further, then the one who's going to end up paying for those higher wages is going to be the end consumer of the company's products. Especially if at the same time you increase your tariff walls against cheaper imports. So, inflation.
See my latest reply to Tom regarding the withdrawal from Afghanistan. Was it disastrous, yes. Would it have happened any differently under Trump, no. And whose idea was it - well, Trump's, but confirmed by Biden, so both.
At the end of the day, there might not be much difference in terms of personal efficiency between a Biden in cognitive decline or a Trump who's never been particularly smart but more importantly just doesn't give a fuck, about foreign policy or anything else. And if a second Trump administration had those Bush or Reagan Republicans that you're talking about as adults in the room who will take the actual decisions, then okay, that could be as good or maybe in your view better than the Democratic adults in the room in a second Biden administration. If I thought we could get four years of a Secretary of State like Condi Rice, Richard Lugar, Colin Powell, I'd sign for that in a heartbeat (though would it be enough to make me vote for Trump, not so much). But after what we've seen during the first Trump administration and even more so in the years since then, it doesn't look too much as if that kind of people would be in those positions, or anyway not in a sustainable way where foreign partners can be confident that they are there to stay and their word can be relied on.
I mean, having a president as ego-obsessed and supremely uninterested in doing his job as Trump would be one thing if at least he'd let others get on with theirs without interfering. But he doesn't do that either. The only way to make sure you remain in his good graces is to completely debase yourself in a way that makes it extremely difficult for any outsider to retain much respect for you - though even after you've done all that, he may still turn on you in a heartbeat and have his followers turn your career into roadkill for some flimsy reason. Exhibit A, Mike Pence.
I don't necessarily disagree on that last part, but given the current era of hyperpolarization and razor-sharp majorities, plus the VP casting the tiebreaking votes in the Senate, I'd be quite surprised if that ends up being a different party than the one winning the presidency. Although I guess in the event of a Biden victory, there's still a good chance the Dems might win the House but lose the Senate.