I usually ran code-server on the Raspberry Pi and connected to it from the iPad to read and write code, but I found GitLab’s built-in Web IDE to be quite usable too (it’s based on code too afaik).
As for reading code for review purposes — if you don’t need to compare it locally, and built in Merge/Pull Request review of GitLab/GitHub/etc are enough, experience on iPad isn’t much different from desktop.
Doing all of this without a physical keyboard makes it much more painful though.
TL;DR: use GitHub/GitLab’s web interfaces, have a physical keyboard.
Light bedtime reading. At bedtime, there's no deadline pressure to stop you working through small points carefully. And then there's the subconscious factor, where your brain will keep working gently on your problem overnight. And allow you to have a 'sudden insight' at some later time.
I wouldn't do code reviews a la Github because the web browser is utter shit (sorry, if anyone reading this has worked on it—i love the rest of the product!) and obviously there's no app for it.
Granted, it's usually just web stuff, nothing too complicated.
Ok, I lied. Sometimes it's cafeteria and not the bathroom.