It would be super cool if unity had an app for mobile which allowed programmers to code on their mobile phones and it instantly syncs with the project on your computer. I realise apps can only be a certain size on mobile and putting the whole unity editor on mobile would be impossible although visual studio for mobile would be awesome.
To summ it up, what you want is effectively:
- A repository, which most people already use
- A way to access this repository on your phone
- A code editor to work on your code on mobile
This really has little to do with Unity itself, not to mention that there is probably only a hand full of people who would even want this. As far as i know, there are code editors for mobile. There are also ways to check out repositories mobile. So combining some of the already avaliable tools should give you the functionality you desire.