The GitHub cli tool gh now has a search feature! I recently had a use case requiring DependaBot to rebase all pull requests across the GitHub organization repositories.

The following shell command did the trick by piping the output of gh search prs to gh pr comment:

gh search prs \
  --owner googlemaps \ # replace with GitHub owner
  --state open \
  --label dependencies \
  --limit 200 \
  --json "url" --jq ".[] | .url" \
| xargs -n 1 -I{} \
  gh pr comment -b "@dependabot rebase" {}