A repository's Pages URL is usually absent from its `homepage` field

Fact

has_pages on the repos listing is a reliable flag for "this repository serves a GitHub Pages site", and it needs no authentication for public repositories. The URL, however, is not there: homepage is a field the owner sets by hand, so it is null on most repositories that publish Pages, and enumerating sites by filtering on a non-empty homepage silently misses them.

The project-site URL is derivable instead — https://<owner>.github.io/<repo>/, or https://<repo>/ when the repository is named <owner>.github.io.

Why it matters

The obvious query returns a partial list that looks complete, because every entry in it is correct. There is no error and no empty result to notice — just fewer sites than the account actually has.

GET /repos/{owner}/{repo}/pages does return the real URL, but it needs push access, so it is unavailable for enumerating someone else's sites and unavailable to a CI token scoped to a different repository.

How to apply

gh api --paginate "users/OWNER/repos?per_page=100" \
  --jq '.[] | select(.has_pages and (.archived | not)) | .name'

• Build the URL from the repo name; fall back to homepage only when it is set and points off github.com, which is how a custom domain shows up.
• Filter out archived repositories — the flag stays true after archiving.