Potty Training Advice

I need some advice from seasoned parents!!

I have a little boy, he’s my first child, who is a couple months over 2 1/2. I have tried 3 different attempts at potty training him, months apart from each other. Each time I try the 3 day “commando” method. We don’t even get through the first day… He cries and cries for a diaper. My second attempt I ignored the pleas for a diaper and made him deal with being naked from the waist down. He held his pee/poop all day long until he finally had a painful accident (peeing). I felt horrible and gave up. I tried again today and the same thing, cries and pleas for a diaper. My husband decided to put underwear on him and he peed and didn’t tell us and was running around in wet underwear. How do I get past this crying for a diaper thing? It just makes me feel like he’s still not ready but he’s got like 4 1/2 months until he’s 3. He’s very smart, he can communicate just fine, but he’s usually unfazed by a wet/dirty diaper. I want to get him potty trained before his baby brother is born in a few months, but I don’t want to force it either. All the research I do and even my mother in law all say DO NOT FORCE IT. Do I just keep waiting and trying again? Are there better/different approaches I can take? Any advice is much appreciated!