>but I've been trying to acknowledge to myself that, generally speaking, most of their voters mean well [1], even if they are voting for politicians that I think are disgusting.

Some remedies:

(1) Actually talk to those voters and get to know them at a human level, don't just group them as an undefined mass of "people who vote badly".

(2) Try a mental game where you imagine your side has the wrong arguments or is talking from privilege, etc., and study what the other side is saying (even the naive people there, but even more so the smarter and less naive people there), trying to see how they are right. Find arguments why your (current) position is wrong.

(3) Then try for a month, to see all those sides (voters for R or D for example), as an outsider, who doesn't agree with either side. Check what people not belonging to either side have to say - e.g. political outsiders, academics doing a critique of both parties, pundits, commenters, and philosophers from a previous century not giving a damn for today's politics.

(4) Finally, see the ideas of today as from 2121, the same way we see the ideas of 1921 today. Then as from 3021 B.C. Don't assume a monotonic increase in agreement of the future with your current ideas, or the prevalent ideas of today, but that history goes back and forth in ideological fashions (including what's "good").

>[1] Though I have to say that some of the "build the wall" rhetoric around immigrants has made me question this.

Here are some examples of (2) in this case:

(1) Note that the idea of borders and citizenship is already the idea of a wall. And nobody, not even the "good guys" you voted for, ever challenged those.

(2) Note that the wall is defensive (we don't want no any more to come) and not actively harmful, then see how the good guy politicians that are feigning the idea unacceptable and inhuman, often advocate for foreign wars and interventions that actively harm millions.

(3) Note that those in favor of "building the wall" might have issues in their communities or work that e.g. a FAANG engineer might never experience as problems because they have different job prospects. Consider if your private interests were directly harmed by immigration (e.g. you are living in close quarters with poverty striken immigrants, taking to petty crime and so on, or because your low skill job industry prefers immigrants to lower costs and you're either out of a job or have your wages slashed).

And inversely, if you're say a Republican:

(1) Note that your family doesn't have very deep roots here. Just 400-200 years ago they passed some other people's non-wall (and killed a lot of them) to grap the land. If, say, you're a Kowalski or a Smith, you're not fooling anyone that you're the rightful owner of this land. B...tc please, your ancestors didn't come traversing the Bering Strait, you're not Clovis. If you're, like, second generation, your parents were bona-fide wall climbers. Perhaps they did it legaly through Ellis Island for example, but do you think they'd stopped if they were denied there, but had some other way in?

(2) Note that the Wall is established on land (TX, NM, FL, AZ, CA) stolen from the very country its people tries to keep out. It's even in the names of the states, all Spanish. Who are you fooling?

(3) Note that if you're out of a job, it might have more to do with clean shaven, suit wearing anglosaxon bosses preffering cheap immigrant labor, and less about the immigrants themselves. Plus, if those immigrants were legitimised, and given an easy way to citizenship, would they still be a cheaper option to undercut your wage?