Great news. Was going to ask same question :)

I submitted 2FA Notifier to the FF store and got approved, but it still stuck in "Awaiting Review" state. This is my first time working with the FF store, so figuring things out as I go. If you've got any tips/resources/etc that might be helpful, shoot them my way!

I'll post here again once the extension is available to install via the FF store.

The extension is now accessible in the Firefox store [1]!

Please shout if there are any weird bugs in FF. I do test it in Firefox before publishing, but Chrome is my main browser so I catch things there more quickly.

[1] https://addons.mozilla.org/en-US/firefox/addon/2fa-notifier/