Long post:
TLDR- could be poor introception related. This can be a sign of ND (though not always). Try a different approach to motivation - ie waaaay more special than chocolate, and see what happens.
It took us nearly 2 years to fully crack potty training.
i know that sounds really depressing - it was but only when I compared him to my friends kids. When I just accepted him for who he was it was just “one of those things” and we tried to celebrate the victories.
poos were first, I can’t really remember at what point he started only doing poops in the toilet with a little seat, but this was more consistent earlier than the wees, which truly we only cracked not long before his 4th Birthday. But we have now done it.
my primary tip is to have lots of cheap clothes/pants and a great washing machine. Wash with the correct amount of soap powder - very few people in the UK seem to - I learned about this when we decided to do cloth nappies.
During the potty training period I realised it’s very probable that our son is ND. It runs in our family, and he exhibits some behaviours that are quite typical. However these behaviours would be missed by many because he is also extremely intelligent and has been very articulate from an early age, so I didn’t see it at first. He is awaiting diagnosis.
However the more I read the more I came to understand that his slow progress with toilet training was likely part of ND, specifically having relatively poor introception compared to NT kids. He couldn’t seem to feel that he needed the toilet, or that he had wet himself when doing something he was absorbed in - and he gets hyper focused so it was happening a LOT - sometimes more than 6 times a day.
he also exhibited some of the behaviours you describe such as not appearing interested in what you have to say, refusing to tidy toys (can be a sign of oppositional defiance which is a common ND trait), dumping toys, being “willful” etc.
not having a diagnosis hasn’t prevented me from parenting him using techniques usually aimed at ND kids. If you’re not already reading about these techniques they might be worth glancing over even if you don’t think your child is ND - in my view they aren’t “just” for ND kids. Many are pretty common sense but different to how I was raised so seeing them written down helped hugely.
specifically on potty training I finally realised that we were going to have to bring out the “big guns”. My son has a couple of special interests. I promised him something to do with his interest if we could manage all wees in toilet for a day, same following day, then had to go two days for something better. Then 3, then the weekend, and then it was pretty much done. The rewards weren’t chocolate but very cheap toys, but ones he was really coveting and motivated by. I couldn’t believe how well it worked!
We haven’t looked back since I did this.
it does get better eventually! Don’t give up hope, and if possible try not to compare him to other children.