In my experience, converting to LaTex is hard, but writing in LaTex from the start is trivial. That's how I write my novels, and I don't need more than the occasional \emph{}, \ldots and \chapter{}, and remembering to use `` when opening dialogue. Could you do that from Papyrus Autor?

The printed book you have self-published but without KDP or bulk self-publishers, can I ask how you went about it? Did you take your LaTex / pdf file to a book printer, use some other self-publishing service...?