Every 30 mins sounds overwhelming even as an adult.. for my son it took a long time but taking him in the morning then every time I had to go worked. (The part that took a long time was outside of home)
We taught asl Potty sign it’s a very simple sign maybe can try to teach that. Supposedly your aren’t to ask it in a question format and not give them an option as they will almost always say no. Just take him potty sit him down to try with 5-15 min if he isn’t going he isn’t going. Make fun bathroom faces/sounds If he has issues with clothing I’d start with underwear so y’all can weed out which ones he prefers Instead of after every meal u can do before and after nap/bedtime
Could you try a sign/menu by the potty with options showing pee pee, poo poo, or nothing? You could still take him every 30 min, but he could point/tell you before he sits down if he has to go or not? It's hard if he says no to everything.... Giving him space might be the best course.