Before Trump, a lot fewer. There is a well known phenomenon of GOP governors in deep blue states (e.g. Christie in NJ, Schwarzenegger in CA, Baker in MA, Scott in VT). This is a lot rarer in deep red states. There are a lot more red states than blue ones, but it's still harder (not impossible) to find recent democratic governors of those states. Senators are a bit more proportional, mind you.

Trump has sort of killed this phenomenon - partly because his brand has rubbed off on other Republicans, and partly because they have been running more extreme candidates even in blue states. Before Trump, though, it was not even close.

I don't know any Democrats who avoid voting Republican because they consider it a "sin." The Democrats I know avoid voting Republican because they think that Republican policies are bad for the country.

I also see Democrats perfectly happy to see Democrats justly convicted of crimes. The Republican approach is to defend members of your "team" at all costs, no matter how guilty they are. The cult of personality is much strong on the Republican side.

All Ds I know pre-Hamas invasion were pretty much the same and would never vote out of party lines, but they wouldn’t say it that way. Rs say it more explicitly. All Ds pretend to be “independent” but they will find a way to rationalize their D. Both bases are quite sticky. There are events like Hamas that suddenly make a change in specific subgroups.