My two cents...
Your son is way behind the 8-ball in 2021 college baseball recruiting. There is much more to college baseball recruiting than showing up at a showcase or tournament. There is a lot of hardwork that happens outside of the baseball diamond and gym focused on researching colleges, coaches and especially communications. I'd suggest your grandson & parent get with his travel coach or high school coach and come up with a plan to reach out to as many schools as possible. It seems like your son is getting some showcase & tournament exposure but not taking advantage of it or following up (email, text, phone call) with the coaches. Otherwise, he'd probably have some offers or serious interest at this point. Your grandson has some assets (size & athleticism, GPA, hardworker) that coaches may find interesting but your grandson has to remind them that he is available and looking for the right program.
This recruiting process is all about numbers. Find 30 programs that he is a good fit for, reach out to them and see who is interested. Going back to my earlier statement about involving travel coach or high school coach; your grandson can divide and conquer those 30 programs by dividing up the list among himself and his advocates to reach out to those college coaches. He has to get on the offensive with this recruiting process.
As always, JMO. Good luck!