Several considerations.

1. A minimal setup will reduce cost and (perhaps) energy requirements. Before dismissing phones, look at large devices (phablets). Such as the Galaxy Note. They are still quite small if you have to do serious work, but they are surprisingly capable. Pair with a Bluetooth keyboard.

2. If you need to run a standard computer, well, we've lugged a MacBook Pro. A better alternative, if you live by Windows, would be the Surface Go. Diminutive, impressive computer. 6-9hrs on less than 4mAh battery.

3. iPad Pros are powerful machines. Nothing really comparable in the Android camp. But since an iPad + keyboard is roughly the same weight as a MacBook Pro, I'd go for a computer.

TL;DR - by all means try to do your thing on a phone. If really impossible, a Surface Go or a MacBook.