You and I (and other like-minded folks) don't lie to ourselves (mostly). We know what Biden screwed up, for example. We know we're progressives (in many instances). They lie to themselves about being fascists (not all, of course...but his hard-core supporters are).

Perhaps, but I think you're doing something similar to what they do sometimes - which is project the lunacy of the crazy fringe onto the much larger group that's just deeply conservative. Only a small fraction of Trump supporters genuinely believed that there was an actual sex ring in a specific basement in a specific pizza parlor, for example. You can find nutjobs and deeply ill-informed people in both parties' bases, and there's a whole cottage industry of influencers/attention-seekers who serve those examples up to partisan enthusiasts in exchange for eyeballs and clicks.

You and I tend to lean more on the skeptical end of a skeptical-credulous scale, and by definition we're political junkies relative to the rest of the population (because we post here). But that doesn't mean that all Democrats or progressives are like us - any more than my many sane and well-informed conservative friends and colleagues mean there aren't Pizzagate believers. If you have a center-left media diet, you're not going to get exposed to the craziness on the left except to the extent that it really escapes containment (like vaccine skepticism) - but that doesn't mean it isn't out there:

france24.com - Bending of reality US liberals stoke political conspiracies

Meanwhile, ravenous consumers of LibsofTikTok and similar fare are going to be convinced that it's the Lefties that are stark raving mad, filled with false beliefs and self-delusions. You don't have to go far to find some progressives who are convinced that Vladimir Putin has actionable blackmail intelligence giving him complete control over the President, for example - even though that's certainly hooey.

Most deep conservatives convince themselves they're not literal fascists the way that most progressives convince themselves they're not literal socialists - by recognizing that adopting singular policies that are also common features of those societies doesn't mean you're that society. Having a few state-owned grocery stores or nationalizing health insurance doesn't make you a socialist, even though those would absolutely be features of a socialist state. Advocating the most minimal due process rights for deportation proceedings similarly doesn't make you a fascist, even though a fascist state would have that. Etc.

There's almost certainly differences, of course. Conservatives tend to be much more religious and evangelical, for example, and so assign far more credibility to religious statements about the world relative to scientific statements than you or I would.

I think pointing to misinformation and delusion, rather than genuine differences in values and conceptions of what is a good society, will lead to misunderstanding the political divide. It's comforting to think that your opponents are simply fools and ignorant, rather than people who genuinely have different values or beliefs than you do.