[jcynix]

You can install Termux on Android devices and use Emacs there. I use it on more or less read only on the smartphone and actively on a tablet. Both rsync with my desktop from inside Termux.

And Orgzly has already been mentioned.

[Wildgoose]

I do this on a Gemini PDA-phone with an integrated keyboard. It's great!

[Pumafied]

Oh my word that device is awesome thanks for this comment!! I know what I’m going to be picking up in the future

[Wildgoose]

Take a look at the AstroSlide 5G phone with integrated keyboard that they are releasing early next year - I have mine on order.