2022 was my first season watching D3 baseball, so fwiw: My son is a rising sophomore pitcher and his D3 team has 6 or 8 guys who can touch 88-90+ (and I mean touch that while actually pitching, not just trying to throw as hard as possible for a radar gun reading). These guys typically sit around 85-88 (and a couple of them do have problems with command). The two freshmen Ps who saw game time last year both touch 89-90.
Those numbers seem pretty typical among the stronger D3 teams I saw in 2022, with the occasional lefty throwing lots of junk at 70-75. And good D3 hitters didn't seem to have trouble getting the bat on 87-89 mph pitches if a pitcher can't locate his fastball and change speeds.