Here are my picks for cross-overs:
For the Dems, I wonder if Henry Cuellar in TX voted for Trump. If Trump's perception really did improve that much with Hispanics and he's relatively conservative compared to the average Hispanic voter. I can also see Tulsi Gabbard having voted third party.
For the Reps: I'm guessing Paul Mitchell in MI didn't vote for Trump if he actually left the party over Trump's fraud claims. Amash clearly didn't and it wouldn't surprise me if Upton didn't either. I can see Adam Kinzinger potentially also voting third party, given he's pretty moderate and has been a pretty vocal anti-Trumpist post-election. Romney said he didn't vote for Trump and I suspect he may have voted for Biden. I would guess Murkowski didn't but I don't think she voted for Biden. I'm pretty sure Collins voted for Trump given how she framed her election vote during the campaign ("Refuse to comment").
EDIT - just realized this is about the new Congress and Paul Mitchell and Tulsi Gabbard won't be part of it
Henry Culler I believe was one of Biden's top donors at one point, so while I see where you're going and at face value it would make sense, he likely still voted for Biden at the end of the day.
Oh, I didn't know that and wouldn't have expected that. Although, Biden does actually seem pretty moderate imo so it doesn't shock me that moderate Dems would be nearly unanimous in their support for him.