TeX Writer developer here. Very flattered to be included in the author's workflow. Sitting at the core of this process is WorkingCopy, which has the most sensible integration with Files app that it simply keeps all files local. After one or two emails with its developer, we managed to get the coordination working rather quickly. The intersection of LaTeX & git & ipad users are very small, but it is a joy to see that apps can work well together with just a little bit of effort.

For iPad to function as a real computer, I think what we need most is a shared file system that can be accessed by all apps alike, with some sort of access control.

btw: Never expected that someone would dump the TeXLive tree into texmf-local. Nevertheless, glad that it works.