Personal use Xposed module. Using DexHelper to search for most of the classes and methods during runtime.
- https://github.com/LSPosed/DexBuilder
- https://github.com/yujincheng08/BiliRoaming
- https://github.com/cinit/QAuxiliary
You can just build FairEmail and Flexbooru from source code or you can support developers by purchasing it.