Toilet training accidents

So a little bit of background to start, I have two boys one who is soon to be 7 and my youngest who is 4 in a few days. My eldest toilet trained day and night before he was 3 about 2.5years old and was a wizz certainly the exception to the rule I’m under no illusions 😅

Now my 4 year old we have been toilet training (daytime only) since about 2years 9 months or so, so we’ve been training over a year and I can honestly say there has been very few days we’re he hasn’t had an “accident”(pee it’s not poo anymore thank god) he shrugs his shoulders when you ask why he doesn’t go to the toilet and just says I dunno like he just can’t be bothered, he’s never upset like I see other children get. I’ve tried taking it back to basics several times and from that now we’re at the point now where at school he’s fine stays dry and at other people’s house he stays dry(which yes is better than nothing at all I know) but at home he will always pee himself. It’s driving me crazy we’ve seen doctors there is no underlying physical cause for him to do it and our public nurse has referred him to a toileting clinic doctor but the list for waiting is forever. I have said to him several times If he’s not ready it’s ok we can put on a nappy but he says no or if I do put one on him he just takes them off anyway. Basically I’m just looking for any tips tricks or advice really because I’m getting worried and stressed by it and I don’t want to get angry with him but I’m at the end of my tether so literally any advice I think will help a momma out! 🙈 I would like to see this issue resolved for me and him before our next baby comes along. It’s like he always has to release abit of pee before he’ll even realize he needs to go to the toilet and he gets angry if I ask him does he need to go all the time.

He’s definitely a live wire child but he’s got he’s witts about him too and I’m just not sure where to go from here tbh 😓