Uhm why not Typst? I published my thesis and another book in it and it worked great. They are also working on HTML output which should make it easier to create EPUBs. Until then Pandoc should work I think
On Pandoc I agree. Word custom styles is possible I believe but it will be a mess (as usual with Word).
Works great on my MD -> DOCX/PDF/HTML workflows but not the inverse, alas.