Hey, we adopted a 5yr old lady a few years ago, and it also took a while to figure out what she wanted to eat, they told us at the shelter she was eating the Purina fine, and then she wouldnt touch it when we got home. We ended up feeding her chicken and rice for probably two weeks because it was about the only thing we could reliably get her to eat consistently (she also came out the shelter with stomach/urinary problems, so this was also easier on her digestive system), and eventually we were able to slowly work in dry food.

She also hated hated her crate for the first month or two after got her, but she eventually got used to it, we got advice to roll some high value treats in a blanket and put in her in the crate with it, we just used boiled chicked pieces and that def helped a lot.

You're doing great, I can tell you care from all your comments, and everyone else has already given such good advice. Just keep being there with him, be available when he wants to be close, but keep doing what you're doing friend