How about after school sports like martial arts at a private studio? My son has been practicing martial arts since he was young and now has a second degree black belt, earned with lots of time and grueling work. He is also part of their high-performance competition team and has won medals. Since it is not a school sport, there is no varsity letter associated with it. Would this extra sport count as a “varsity letter” as well?
1st, congratulations to your son on earning his second-degree belt, it's a huge accomplishment requiring years of commitment.
During our son's admission cycle, he reached out to his admission rep asking about this. He had done TKD for 10 years, competed, taught, ran testing, and earned his third-degree black belt.
The admission counselor told him to list it as varsity and to list 'captain' as he had led competition teams and taught. He spoke about it in other areas in the application and essays and interviews.
He included every medal he won at every competition on his resume and listed the major ones where he could on his application in 'other' areas.
I wouldn't discount that level of commitment and work. And his admission rep agreed. His teaching also could be highly regarded since he taught both kids and adults. And had to have interactions with parents and special needs students. That component was something he was able to mention in an interview.
I know it isn't a traditional 'high school' sport, mine didn't do any of those either. I would suggest your DS reach out to his admission counselor for guidance. It's early in the cycle, he has time to get proper guidance.
DS participated in USNA TKD briefly, but Covid and a long injury ended that.