Ok, Biden got 1.995M votes vs 595k for Trump in PA via mail-in/absentee. So that metric although positive for Harris is lower (2.5x vs 3x) than Biden’s advantage. Let’s assume she takes 60% of those independents (142k). That’s still only 2.66x advantage over Trump.
I guess what is positive is that in pure numbers Trump is probably looking at a ceiling of 400k mail-in votes vs 595k in 2020 in PA.
Edit: It’s also worth pointing out that with covid Democrats were far more likely than Republicans to register to vote mail-in. So some of the attrition to Dem early voting may be baked into them turning out in-person as opposed to Republicans who were far less inclined to vote absentee in 2020.
Also national data on mail-in voting in 2020 via Pew: Nearly four-in-ten absentee or mail voters (39%) say they had never voted by this method prior to this November’s election. Biden absentee or mail-in voters were slightly more likely than Trump absentee voters to report not having voted this way in the past (42% vs. 34%).