As a maintainer of a popular and actively developed open source project, I would totally use the app to respond to issues and pull requests if it were usable. Unfortunately, the app is a dumpster fire, so I just use github.com.

If you do use android for development, you wouldn't need a github app to push your code to github. You would need a git app, and several great ones exist.

I meant to use it as a communications tool, not for pushing/pulling/etc. Responding to issues, accepting/declining PRs, and so forth.