Logseq has an Android app and clients for the usual desktop platforms. It stores as .md files. It meets your requirements. I’m not sure why you’re focused on Firefox support?

One I have my eye on is Silverbullet.md. the creator recently promoted it here and it has some nice ideas. It’s a web app that you self host. Behind the scenes everything is stored in .md files.

This is very cool, and I’ve been watching the project for a month or so.

I like the query setup and the templates look very interesting. One of my biggest complaints about Logseq is how much of a pain simple query operations can be.

A few things make me hesitate a bit:

• I’ve been burned on single-dev passion projects in the past.
• As a self hosted web app, it’s a bit more difficult to manage on a company owned machine. I know Electron apps get hate, but that would ease some pain here.
• The rapid pace of development is both exciting and worrisome. For example, a recent update completely changed the underlying templating engine from a well-known open source solution to a custom solution. I worry if I rely on this, something might catch me by surprise.

What are your thoughts on those concerns, OP?