I did major refactors and quality of life improvements (such as the app gracefully handling being backgrounded during install, preventing screen from turning off, etc) for Android Boot Manager github.com/Android-Boot-Manager/App
I forked the official Google Cardboard SDK to remove proprietary code in the QR code scanning part, which allows to build 100% open-source apps for Cardboard github.com/googlevr/cardboard/pull/472