There is AIDE for Android, and also Termux if you're rooted, so this is not necessarily a new idea.
tl;dr. it's too impractical and limited, you should use your phone.
Longer answer:
It's possible, but it's so impractical that nobody wants to waste any time creating it. Also let's not talk about the limitations of the hardware in terms of both processing power and usability.
The syntax highlighting would be unbearably slow, fast typing on a custom keyboard on a non-multitouch screen is painful, the amount of time it would take to build a single source file (it takes a lot of time even on a powerful beast of an atomreactor gaming rig), and the amount of RAM you need to hold the IDE and the compiler's data.
Considering how little RAM you have, without implementing pagefiling/swapfiling in usermode it's not possible at all. (implementing swapfiling/pagefiling IS possible, but SD access speeds are so awfully slow that you'd be better off streaming it via WiFi, at which point you'd just use your phone).