My guys ('17 and '19) had similar stats as your son's and are at HA D3s.
RJM;s advice is critical: contact coaches and find out where they're gonna be. Send video. Stay in touch. After picking the event that will allow your son to be seen by the most coaches, go have a good showcase. Doesn't really matter which event it is, of the ones you mention (though I'm not that high on the AZ Academic event for reasons I'll share below.) Go where the coaches are, and let them know you're coming.
Both my older guys got multiple d3 offers after their first showcases during the summers before their senior years. One was at HF, the other at Showball. We did other showcases but the boys did get offers after only one. The later showcases gave them more options and they didn't end up at the schools that offered first.
The AZ academic showcase is a crapshoot, at least actually getting into the academic game is. The tryout is okay, but getting into the game itself can be challenging. If you're going with a team that's good. But the senior one is relatively late in the recruiting cycle. Scary to wait that long, so that's why its lower on our list. Fun event, though, and less draining than HF or Showball.
We don't have any experience with I95.
I don't mean to sound cavalier, or discouraging, but in your case (and in mine, frankly, with my upcoming '22)) the best showcase is the one your kid does well at. I think Showball/HF/even Stanford could be that one showcase, but lots (all?) of coaches want to see guys more than once. That may not be as necessary with pitchers, though. Velo plays. command plays. Coaches may only need to see that once. I don't know.
Get that list of schools together and go from there. Pick an event later in the Summer. Serious doubts about the early summer events actually happening. Who knows? These HF type events may have to wait until fall. What fun for everyone!