Why is this in past tense? Guix development is active. It's just Nix is more popular and it's understandable since it's the original idea and it's older.
Guix even has a very active, high-quality blog where maintainers detail major technical accomplishments, long-term goals, etc.: https://guix.gnu.org/en/blog/
From here it seems like they're growing and advancing well. I wish I could find ready historical data on the numbers of packages and services from, say, 4 years ago vs. today, though. I could have sworn Repology used to show year over year stuff but I can't find it now.
Why is this in past tense? Guix development is active. It's just Nix is more popular and it's understandable since it's the original idea and it's older.