Use Pandoc w/ Typst. I've published many books using it.

In fact, just had a friend with a traditionally published book who is now self-pubbing ask me yesterday about my tools. I recommended Pandoc and Typst. He (surprisingly to me) had never heard of Typst, but within the hour replied that (with the use of AI) he had a great-looking template for the book. (Try doing that with LaTeX).