I don't know a whole lot about the regulations around NIL and international students, but I think it mostly revolves around labor. If the NIL requires no labor from the player involved, then supposedly it's fine (although I'm not sure what constitutes labor to the NCAA).

It could be a bit of a headache to navigate but, for the players themselves, they can probably push a lot of the logistics onto the schools. Jumping through a few hoops may be worth it to them considering most guys in euro leagues are making significantly less than the top NIL earners.

As far as competition, I could be totally off base on that one. I don't follow the euro leagues closely. But I will say, if a budding superstar euro player is aiming for an NBA career, it could be a very savvy business move to play a year of college ball stateside and build a brand in advance.