IMO terminals are still the fastest way to do a lot of things on a phone, but it's a much better experience on Androids with keyboards for the purpose.

And even on an iPhone, it's just fine. Python works really well as a shell for quick calculations, and you can use a script with the -i flag to make it more accessible.

And I regularly ssh into my servers from my phone to run some small routine tasks.

Both these kinds of tasks involve extremely minimal amounts of typing, and little to no reading of output. So the small keyboard of the phone is not annoying, and neither is having a small screen.