No boy should grow up to be a sitzpinkler.
When they come out of diapers it is easy to transition to standing in front of the toilet. All of the brouhaha about pee everywhere notwithstanding, it is easy to hit the target too. At that age the distance between them and the water is minimal. Some even need a stool as noted because they’re not tall enough. What’s the boy afraid of? Missing the toilet? Where did he learn that? He misses, he adjusts, he finishes, maybe he wipes up the misadventure. He needs to practice at home, with no big deal about a sprinkle here or there. Where’s the father, brother, trusted male friend in all this? No kid should have to struggle with a basic bodily function because the person in charge of him doesn’t have the equipment to show him what to do.