Android with termux is a pretty good approximation to a handheld GNU/linux machine. You can access the files created by other apps on the phone, so it's easy

Android with termux is a pretty good approximation to a handheld GNU/linux machine. You can access the files created by other apps on the phone, so it's easy to cat text files in your Dropbox area, etc. you can wget files from other machines. You can ssh into the phone from your desktop machine, and then work on the phone with a real keyboard. GNU compilers work on the phone. About the only complaint I have is that I have not found an X11 server app for Android that is useful, and it's not been for lack of looking.