I have created my own fork of Nixpkgs that reintegrates the changes to the Android build environment and other mobile app build functionality. It can be found here:
https://github.com/NixOS/nixpkgs/pull/50596
The changes are fairly complete. We need to change a few subtle things (e.g. buildGradleApp).
The biggest challenge is to make stdenv.cross work again. Since I do not cross compile much and I haven’t touched this code very much, I could use some help in getting this functionality fixed.
Please let me know if there is anything else that may break and requires fixing.