Per-file license notes in Nixpkgs

Dear Nixpkgs maintainers,

in the context of this year’s Summer of Nix efforts around a new monorepo for software projects funded through NGI we’re yet to choose an appropriate license. Our project leads at NLnet would prefer (weak) copyleft to ensure that public money keeps translating into public code, and one option to enable that would be MPL 2.0.

Now of course we want anyone to pick up the program participants’ work and upstream it to Nixpkgs for broader visibility and ongoing maintenance. With MPL that would require a per-file copyright notice, possibly in the form recommended by REUSE. While this is something we could easily implement for NGIpkgs itself, it may not be welcome in Nixpkgs.

What do you think? Would that work out? Alternatively, do you have suggestions apart from licensing under MIT?

Thanks for your help!