This has actually been calculated. If we used 50 state-level electoral colleges in 2020, where each county was awarded winner-take-all, the result would have been 378-160 Biden.

WI would have flipped to Trump — but NC, FL, and TX would have flipped to Biden. https://t.co/0uGXy6ETdY

— Matthew Chapman (@fawfulfan) December 2, 2021