Potty training - suggestions

My son is 3y5m old

He first started pooping on the potty about 5 months ago- he literally has just said “I gotta poop” and will go to the bathroom on the toilet by himself. Even in public he will tell us rather than poop in his diaper (obviously he needs help wiping) He has not had any accidents with pooping since he started going on the potty to poop.

He does great peeing in the potty when he has nothing on (no diaper, underwear, pants) he pees standing up which nobody told him to do he just watched his dad do it a couple times & he started to do it lol. He does not pee on the floor at all when he is naked throughout the day & will always go to the bathroom if he has to pee or poop. When he wears underwear he will pee in them unless I tell him to go pee.

Do I just continue to keep him naked throughout the day? How do I transition him into underwear? When do you start no diapers overnight?