My DS was/is really similar.
From 16 months he has used the potty by himself - just taken himslf off to it, but ONLY when he has had a bare bum. So he has not worn pants/trousers/nappy in the house for about 6 months!
It has taken me that long to get confident enough to try it outside the home though. We tried training pants, and washable and disposable pull ups, but ll of these seem o feel like a nappy to him, so he wees in them. Even normal pans trigger weeing!
So we spent a few weeks wearing just trousers in the home (no pants), and he has slowly started to tell me when he needs to go.
Ad this past week, I have taken him about in just trousers, and we have had accidents, but more sucesses. I do have to ask him quite a bit, as he is still not likely to tell me when he needs to go (I think he is just distracted by being out and about), and on a few occasions, notably, in the middle of Sainsburys, he has told me he has needed a wee and has held on while we dashed too the loo! Hurrah!
He is 22 months.
Go for it! I am so happy to be washing the odd pair of soggy trousers, rather than all the faff of nappies.