How to potty train a boy

I am at a loss. My son is just turning two and knows what going potty is and has no problem flushing toilets or being near them. But I can’t get him to take his pants off and sit on it.

He will sit on it with his clothes fully on, but that’s it and only sometimes. He also never complains about a wet diaper. He will go all day without a diaper change and not complain once. I was thinking of getting him underwear and letting him just pee on himself, although that’s a hassle. But what else can I do?

Thank you guys