This may be one of the most thorough threads addressing the OP’s original questions that I have read here on CC. I agree with all the advice given and here is our anecdotal evidence to add to it.
We have two Daughters who both did the engineering academy (Project Lead the Way) at their high school. First Daughter went to a college summer engineering program and that along with the academy cemented her interest. She only applied to state flagships in the south and chose UF. Graduated Magna Cum Laude in Civil Engineering and has a great start in her career and for now, loves what she is doing. Second Daughter has done 3 different summer academic programs and multiple summer sports camps. She is a 3 sport varsity athlete and based on her academic experience she has initially decided to pursue Mechanical Engineering and maybe a MS in Aerospace. Remember, I said, initially as I could her shifting around as she goes deeper into it. She is pursuing options to play either Varsity or Club in college, but similar problem that few D3 schools have engineering. As of right now, she has been accepted at Mines, Rose, Auburn (Honors), Clemson and UCF (Honors) all offering Merit scholarships. The reason for so many applications can be found in exactly the struggle you describe your son will have if goes down a similar path. She is torn on the small STEM school maybe play varsity vs big state flagship maybe play club debate, etc. etc. Also, she is doing Robotics and Computer Science AP in her Senior year and that may sway her thinking in terms of schools.
As a sidebar, I can affirm that Engineering undergrads are the most sought after students when applying to Graduate Business and Law schools, so if they want to expand upon or pivot in their career after a few years they have options.
All that said, as previously suggested maybe he try one or more of the summer programs others have listed, continue to enjoy his sports and attempt to look at both the small LAC schools with Engineering as well as a few state flagships, especially those that would provide merit (he has the stats to get it). We never pushed our daughters too hard, but we did suggest options and supported whatever they wanted to pursue.
I am sure you are proud of him, he has a problem (aka Opportunity) many young people would like to have.
Good Luck!