Looks like these things are being addressed, although from past of experience it probably will take several years :( (when I started using Nix, 3 years there was a talk about this new thing called flakes, now the version 2.4 already contains it, but it is still locked behind experimental features)

1. https://github.com/tweag/nickel - it is a typed language, that might in the future replace nix language

2. looks like likely is addressed by flakes