You can be in any league, event, tournament, or just High school and there can be scouts, coaches, etc looking at players but normally that doesn't matter much unless your player has already made contact or is on the radar of the people at those events.
Exposure at a event or league doesn't mean anything if they're not really taking a hard look or deeper dive at your player.
The majors have so many players there looking at, they don't normally pay much attention to a rando player, maybe they take a note or will remember if the player contacts them right after or during the event.
Some blind offers may come for a random player that is a standout but those are most likely from small or obscure organizations that don't have a lot of draw.
The contacts your coaches, club, and the relationships your player makes with those at the next level is more important vs any league. Build those relationship and don't worry about which league much, perform at the events, playoffs, leagues or whatever to back that up.