Answering your questions;
"Who would publish it?"; how about you . . . self publishing isn't that hard.
"Who would read it?"; more than you might expect.
As a published author, I thought my first book would be nothing more than a niche book; for USS Arizona and Pearl Harbor historians, and maybe a few more. In fact, I have sold over 400 copies, nearly 300 to the bookstore at the USS Arizona memorial alone. My second book, a young reader story, has not done as well, primarily due to its launch last summer, in the middle of the Covid thing.
Now, if you are at all interested in doing this; and it seems that you are otherwise you would not have brough it up, then look at other modeling books. See what they have, and more importantly, what they don't. That should give you a good idea what to cover.
Now the big factor; cost. If you add art, especially color, then the cost jumps up exponentially. Black and white pictures can be done like text, but color pictures get expensive; and a modeling book would definitely have to have pictures.
"Why do I do this? Because the money's good, the scenery changes and they let me use explosives, okay?"