No one can answer questions about him as neither you nor us on here know him or ever met him.

As about some of your questions. You are asking why he kept showing you he is interested if he wasn't. Well he wasn’t showing you that he’s interested at all. In fact he was showing you he’s not interested.

Perhaps he wasn’t direct but he was clear. He never called or messaged you except in the beginning (you said yourself you were the one initiating). It’s a clear evidence of lack of interest. He did answered two of your phone calls during one of which he was very rude.

Answering two of your calls does not indicate interest. He might be bored or if he had covid cooped up and didn’t mind chit chat.

He showed no interest except maybe in the beginning. But you can’t really expect people to keep interest going towards everyone they come across. Most people who use apps talk to a lot of people. He is likely dating. So people might talk to several candidates but then not pursue them, you kept calling him for a couple of years. It’s unlikely he never talked to another woman during all this. So why he lost interest is no way to know. Met someone else? Found other stuff to do? That’s just how it works. People can’t possibly be interested in everyone they talk to.

Of course he might be a sociopath. Or a drunk. Or married. No way to know. And why do you care?

If you are interested in dating why don’t you try to date other guys? Why fixate on this one?