I don't think NFL teams have a preference for players from Power 4 teams. It's just that Power 4 teams tend to have the most talent on them, especially since NIL and the changing of transfer rules. It wasn't but just 5 years ago when nearly a third of all NFL draftees were from non-Power schools.
I don't think it's impossible for a fringe O-lineman to be drafted in the late rounds from a school like Wyoming, even in this new world of college football. Guys like Caden Barnett and Jack Walsh were not far off from being drafted this year.