Yes, i often do it, although i tend to do quick fixes/small updates there.
I have Termux installed on my Huawei P20 Pro. Emacs performs pretty good on it, even with all my packages installed. Hackerʼs keyboard with the Dvorak layout is pretty close to my physical layout.
Still, itʼs far from optimal. The screen is not wide enough in portrait mode, and not high enough in landscape mode. Emacs, in this scenario, is text-only, so a lot of graphical geekiness is lost. Running our Flask app is OK(ish), but i obviously canʼt run my desktop apps.
So yes, it is possible. But donʼt do it without an external monitor and keyboard.