Yep, still on it! Just super busy with some real-life stuff right now.

The nightly still gets frequent updates. Nothing major, I haven't noticed any differences lately, but it's far from dead!

One small request would be, if you could add an option to open links in incognito custom tabs?

A bit of a late reply, but if you're using Firefox for Android, you can choose to open every custom tab link in incognito mode. Perhaps that might help a little bit.