A couple of US operators list a "valid U.S. passport" as a requirement to work there vs the "legal ability to work..." route. Not sure why that'd be. Kalitta Charters comes to mind...can't remember the other ones:
https://www.pilotcareercentre.com/Pi...tta%20Charters
Flat out U.S. citizenship is required for those Department of Defense contract pilot positions but they're a different sorta gig.