The money isn't even close. Even if a player makes the practice squad of an NFL team, it's still more than they'd get in the XFL or USFL
How much do XFL players get paid? Breaking down salary structure for 2023 contracts | Sporting News
The Sporting News looks at the salary structure for XFL players, and how it compares to the likes of the USFL and NFL.www.sportingnews.com
NFL is about $200,000 for a season on the practice squad, and you're also closer to a roster spot if there's injuries.
That would be quite a gig and you probably don't get too beat up; I doubt there's much physicality to the practices by then.