Also wrote myself a small pandoc function so I can convert #emacs buffers from one format to another in case anyone else finds this useful: https://codeberg.org/theesm/pandoc-convert.el

As alternatives there's pandoc.el which is more eww focused, ox-pandoc as an ox-backend, and pandoc-mode which is really cool but does way too much for my limited use-case. Wanted to keep a simple buffer->pandoc->buffer workflow as that's what I mostly need and use.