Why? It's not an accessibility feature, and desktop OS versions of Firefox still exist. Choosing a hobbled Android device and expecting desktop-class experience is a user issue.

Will it drive worthwhile value? No.

Are there more pressing matters? Yes.

With that said, it's open source. Why don't you implement it yourself? Meanwhile the rest of us have long since moved on from Firefox.

Samsung phones can do things like wireless beam a desktop over to a TV. You can then use a bluetooth keyboard with it fine with Chrome, but not Firefox.