Looking for potty training advice!

My son turns 2 in 2 months and we started potty training him. We had him bare bottom around the house and he picked up quickly, and then slowly moved him into just an underwear. And he is still okay with that and knows when to pee. He doesn’t tell us often, but he just goes whenever he pleases. But when we are out he always has accidents. And maybe twice in an outing to like the grocery store, but we attempt to put him on the potty while out also!

I went on a walk around the neighborhood and before we left he went pee. We came back and he was soaked and didn’t tell me anything. I heard him say uh oh but I wasn’t sure what he was talking about. Is there anything I can do? Or what advice can you give?