[chriswarbo]

Regarding licenses, most (all?) packages in the official nixpkgs repo have license metadata, and you can set your configuration to forbid/allow proprietary packages (the "allowUnfree" option), or use a whitelist (e.g. forbid everything except Flash).

Guix is a GNU project, and doesn't allow proprietary packages in their collection at all.

[lil1729]

Yes. But the amount of information in the debian/copyright file is a lot more than just one scalar flag. I think that level of detail on the licenses is extremely important.