so... tipping point passed, or what?
When Nextcloud finally shipped a credible wiki (the somewhat absurdly-named "Collectives" app), this was finally enough to get me to install it for myself and my business partner. So, currently, Collectives plus the Sync feature ... other apps may draw me in later.
It's okay, not great, still needs UX work. That being said, it stores all its files in Markdown and they are also accessible in the Files app.
Not actually sure if it can be made public, they grafted some unnecessary features onto it in order to call it "Collectives" which might make it a bad fit for such, but I haven't actually looked to see if it's possible.