+1, I love google docs and also love markdown. If there was a shared markdown editor with the same collaborative features as google docs, i'd probably never use anything else.
We use Slite extensively at work. Works pretty well to quickly create/edit documents with a nice editor. When you type Markdown, the content automatically resolves the styling/headers/lists. Multiple persons editing a document at the same time is (of course) supported. And every document can be exported as Markdown or PDF.
Dropbox Paper should meet your requirements. I tried switching to it a few years ago, but the problem is that the other people I'm collaborating with always want to use Google Docs, and when I'm writing a document by myself, I'd much rather just write to a local file.
Agreed, I like certain aspects of Notion, but as a FE dev myself, I think what they’re trying to do is too complex. I don’t see how they could ever make it performant.
Sure, you can add asterisks around things and it will convert stuff to bold, etc, but Notion isn't actually a markdown-based app – the underlying representation of a Notion doc is stored as JSON.