Im thinking Markdown to HTML as a core functionality requirement is probably a must have.
And once the website is up, are we still doing like Github Pages hosting or are there nicer ways to host that don't cost tons.
For hosting, many providers offer free tiers. You could check out Netlify or Vercel.
I host on SourceHut pages [1], because SourceHut is great and it is not GitHub. Also I find that the mailing lists are a good way to let users comment (not that I get tons of emails, let's be honest).
[1]: https://srht.site/