There are some. Marshall Manning is 12 I think, and I read he’s going to a sports boarding school in TN this year. I’m pretty sure football is his sport, although I know he does play baseball too (my nephew reffed one of his games).
A lot of the Colorado Avs players’ kids played lacrosse for my brother’s teams, but their main sport was hockey. My daughter went to hockey camp with Joe Sakic’s son. I will say the hockey players don’t always play in the most competitive leagues when they are little (thus Joe’s son playing with my daughter at a camp for regular kids not superstars),
IMO, yes, because her exposure would have been greater. My daughter didn’t play on the travel teams or the expensive camps because I just couldn’t afford it. One of her classmates did (like $10k per season travel team) and she did get better, but didn’t want to play in college anyway. Her brother was a top ranked jr tennis player, and they all did competitive ski racing, so sports were important to that family.
I think my daughter would have had better exposure with different youth league teams, coaching, and tournaments, but nothing was going to change that she was still very small when she was being recruited as a 15-16 year old. She had a growth spurt as a freshman in college, and doing regular weight lifting that year also helped, but that didn’t make her a 5’8" player (pretty much the average for her sport) or put 25 pounds on her.
Some sports do need more training, or year round training to make it in college. Swimming seems to be one where just swimming for the high school or summer swim club isn’t enough to get you recruited.
Almost all pro Athletes play(ed) a lot of sports. Many football players also played baseball or basketball, even in college. Many play golf. Mookie Betts is a champion level bowler.