Potty training boys

When getting him to sit on the potty he doesn’t leave his penis alone . I don’t mean “playing” with it he picks at it , pulls on it , hits it with toys, scratches it and shoves his finger into his urethra , all while his hands are generally unclean as most children’s are. So he leaves his penis and testicles red and irritated and sometimes actually scratched up. I’ve been telling him since the very day he started touching himself during diaper changes things like “no no baby don’t touch, your hands are icky” “you don’t play with your penis while mommy is changing you/ in public you play with it in private “ “no no that’s owie on your penis” and yet it doesn’t seem to bother him that he is tearing his self up !

Obviously we can’t just let him grab it and keep hurting himself / give himself a UTI. So any advice ?

*edit to add : I’m not telling him don’t touch or play with himself , it’s all the things he’s doing that IS hurting him , you can’t tell me shoving your black with grime fingers into your urethra is something I should be allowing