I think this already exists somewhere, but hasn't been updated in years.
Acceptance criteria:
- Have a Tool Labs script generate a database report on Meta that lists all the gadgets and how many users have enabled the gadget on each wiki, e.g. HotCat: en(345), de(134), fr(34), etc.
A follow-up task could be to get permission to update the report regularly via a bot flag, but that isn't part of this task.