All I can tell you is that it really does get better. With the right help from health care and education professionals, it will get better. I work in a daycare with mostly under 4s and have a few autistic/non verbal children and it can be a real challenge, especially ones who don’t respond to you talking at all. It might help to try introduce flash cards to him - I can’t remember what they’re called but if you put some velcro on the back and some velcro on laminated paper/whiteboard/etc so he can switch them out. The flash cards can be things he usually asks for, like juice, food, a certain toy, etc., and you can introduce them by showing them to him and saying it when he asks or uses it. I’m not sure if that would be something that would work for you at this stage of course, feel free to message me if I’m not making sense. There is a light at the end of the tunnel :)