Exactly. I have a full fledged emacs inside termux. With a Bluetooth keyboard, it is a surprisingly good solution. I bring this set up with me when I am on vacation and may have to do some emergency interventions for work. The only thing I have not figured out is how to re-bind the cap lock key for ctrl on the BT keyboard. BTW, I install emacs via Termux via their package utility. Termux itself is installed via F-Droid on my Android phone. One last thing: I also have tmux running inside Termux. Again, I am always surprised by how well this works.

I use my foldable bluetooth keyboard. Using iAWriter and termux, I can write posts for my PHP and ruby based blogs, run my static site generator and publish via git. Termux lets you make a shortcut that runs commands.

I tried to make gtk3 GUI apps with ruby on termux, apparently termux now supports this new mode that works in the browser, but some libs seem to be missing! I think that would be a cool platform.

I have a foldable BT keyboard as well (generic one on Amazon under different brand names). I find myself not using it because it sits completely flat, which is uncomfortable to type on for long periods of time. My palm doesn't seem to rest on the table, it hovers over the keys instead. Not sure if it's the same for you.

A laptop keyboard is usually a half-inch or so off the table surface, as it sits on top of the laptop base.