Mine was more a general observation. The GH stars metric is attractive to be used for ranking, because so many projects are on Github. But sites like this also work to keep it this way forever i.e. "I must be on GH for my theme to become popular".

Maybe Hugo Themes [0] or Netlify might offer a usage metric on their site. Here are two Hugo themes whose code is on Codeberg (a Gitea forge dedicated to FOSS projects) that still have a presence on Github, probably due to FOMO:

- https://codeberg.org/Lednerb/bilberry-hugo-theme

- https://codeberg.org/cinux/hugo-theme-techdoc

Didn't look on (self-hosted or primary) Gitlab, but can imagine there'd be a whole bunch of Hugo themes there too.

[0] https://themes.gohugo.io/