Potty training has been a damn nightmare. Anyone else deal with this?

I am about to pull my hair out with potty training. Seriously I had no idea it would take SO long and be SO damn difficult. Everybody I talk to always says they got their kid potty trained using the “3 day method” or potty trained their child in a “week” or potty trained their child at 2 I just don’t understand how anyone does it that quick or that early. My son is 3.5 years old I have tried potty training 2-3 separate times since his 2nd birthday and we are still nowhere CLOSE to being potty trained. Every single time he gets it down pat he gets 🤏🏻this close then completely regresses and wants nothing to do with it. He will pee in the potty all day long ONLY if he is naked from the waist down. If he has a pull up on, underwear, pants, anything down there he will pee on himself. The absolute biggest issue we are having right now is that he REFUSESSS to poop in the potty. I mean absolutely refuses even when he is naked from the waist down. He used to poop in the potty all the time so I have no idea what’s happened but he will not do it at all now. He will have nothing on from the waist down and tell me he needs to poop, (he speaks clear as a bell so there is no issue with communication that’s not the problem, he communicates to me every time he needs to poop but he won’t use the potty) he tells me he has to poop, I take him to the potty, make him sit on it for every bit of half an hour I sit there with him the whole time or stand right outside the door, he will refuse to poop and keep telling me he “doesn’t need to anymore” then I eventually let him off the potty, he starts saying again he had to poop but will demand me for a diaper. He will straight up say “mommy I have to poop I need a diaper” I tell him no, no diapers he’s a big boy and needs to go to the potty I take him again and sit there with him again waiting and waiting and waiting for him to poop he’ll say he “doesn’t need to anymore” then same thing over and over until he eventually either poops in the floor or I just put a pull up on him and 5 mins later he’s telling me to change it because he pooped in it. Like I’m just at a total loss here and don’t know what else to do other than just stop once AGAIN and try again later because clearly he is not ready. It’s just getting so frustrating. He’s the only child around this age in my entire family that is not potty trained.