Ah ok!

I ask because well, I'm autistic, though I am the opposite of a picky eater, I'll try anything at least once... but also I realize not all autistic people are the same.

Was trying to figure out if it was possible it was more of a texture/mouthfeel thing, certain flavor group, etc.

If I had to guess, based on all you've said, he doesn't like spicy, and he doesn't like ... basically meat that is substantial enough that you have to actually tear through some tissue, while chewing.

If he'll eat basically small chunks of meat... well pepperoni on a pizza, the slices are often large enough that you have to actually bite through the slices. So, maybe he'd be ok with sausage pizza, where the bits of sausage are fairly small?

That would be my main guess as to what the 'inexplicable' element of his tastes are... he can handle some hamburgers, because the meat patties are likely floppy enough that they're not difficult to chew apart, but I'm guessing if you gave him a rare steak, he'd hate it.

It might be useful to try to see how he'd respond to just like, bacon, at different levels of crispiness?

Also that and he seems averse to spicy. I remember spicy foods being essentially just mouth on fire pain as a kid, but I eventually grew into having a greater appreciation and tolerance for them.

I'd say that even a cured meat like pepperoni would also be what I'd call at least very slightly spicy... whereas teriyaki sauce, in the US at least, is basically extremely sweet and not spicy at all.

But also, as you say, yeah it very much could be that he basically has a specific kind of 'i want this kind of food / mouth experience today / now' in mind.

... if possible, maybe ask him, try to do like a meal plan system, a schedule? At least one meal a day is some kind of known in advance? Just having the structure might be helpful, basically just so it isn't surprising.