You need:

- table of contents

- automatic chapter and section numbering

- cross references and automatic tracking of figures, tables etc.

- different styles besides blockquotes such as info sections, warnings, tips

Imho, cross-referencing chapters, pages, figures, tables and the lack thereof in Markdown is the first and most important thing to check how you would like this to be solved.

Pandoc and pandoc-crossref. Or simply use quarto.