Fantasy Book Request for an 8yo!

Hello! My nephew is turning 8yo next month and I think he would really enjoy fantasy books if given the opportunity.

He’s really advanced-but he’s autistic and his parents let him do a lot of tablet and phone time, but I think a good world building fantasy books would be perfect for him to get lost in.

Some interests: He loves math, numbers, science, space and languages. When he was I think about 5yo he taught himself the alphabet in 4-5 different languages. He just recently started teaching himself some computer coding as well.

Im looking for a chapter book or even a series to try for him. I think he would also love the books that have an actual map to show the way the world is in the book.

Sorry if this was all over the place, I’d just really love to see him bloom in books not just technology. I don’t have the same interests as him, so I just don’t know a lot of books that might hit the mark.