Things that are useful for any wiki, with no extra work from either us or the community:

• the homepage as a framework (including things like the guided tour explaining it)
  • the start module
  • the mentor module
• the help panel as a framework
  • the mentor/helpdesk screen
• the mentor dashboard
• the community configuration system (we might want to hide irrelevant fields, not sure if currently there are any though)

Things that can be useful on any wiki but require some work from the community to set up (ie. the defaults don't really make sense for non-Wikipedias):

• the help module on the homepage
• the help screen on the help panel

Things that could be useful but need some work from us:

• non-structured suggested edits: the existing task types do not make sense for non-Wikipedias. In theory it's possible to define custom task types but it's untested and probably has bugs.
  • guidance: IIRC it does not support custom task types
• impact module (wording like "articles" might need to be rethought, for some wikis like Commons the metric might need to be different)
• also the homepage layout could be improved (right now there is a gaping hole when suggested edits are disabled)

Things that are unlikely to be usable for non-Wikipedias:

• topics, as we won't have them for the foreseeable future
• structured edits

In terms of impact: Wikipedia is about 88.5% of new user registrations, Commons is about 3%, Wiktionary 1.8%, mediawiki.org 1.6%, Wikisource 1%, Wikiquote 0.8%, Wikidata 0.8%, Meta 0.7%, Wikibooks 0.5%, Wikiversity 0.5%, Wikivoyage 0.4%, Wikinews 0.3%. (From the ServerSideAccountCreation schema with hive (event_sanitized)> SELECT SPLIT(webhost, '\\.')[1] family, count(*) count, count(*) / 7919 /* SELECT count(*) FROM serversideaccountcreation WHERE year = 2021 AND month = 7 AND day = 20 */ * 100 pct FROM serversideaccountcreation WHERE year = 2021 AND month = 7 AND day = 20 GROUP BY SPLIT(webhost, '\\.')[1] ORDER BY count DESC LIMIT 1000;.) Enabling on Commons would reach about a similar number of users as deploying on arwiki.

In T284485#7261838, @Tgr wrote:

In terms of impact: Wikipedia is about 88.5% of new user registrations, Commons is about 3%, Wiktionary 1.8%, mediawiki.org 1.6%, Wikisource 1%, Wikiquote 0.8%, Wikidata 0.8%, Meta 0.7%, Wikibooks 0.5%, Wikiversity 0.5%, Wikivoyage 0.4%, Wikinews 0.3%. (From the ServerSideAccountCreation schema with hive (event_sanitized)> SELECT SPLIT(webhost, '\\.')[1] family, count(*) count, count(*) / 7919 /* SELECT count(*) FROM serversideaccountcreation WHERE year = 2021 AND month = 7 AND day = 20 */ * 100 pct FROM serversideaccountcreation WHERE year = 2021 AND month = 7 AND day = 20 GROUP BY SPLIT(webhost, '\\.')[1] ORDER BY count DESC LIMIT 1000;.) Enabling on Commons would reach about a similar number of users as deploying on arwiki.

Note that deploying to Commons/Wikidata will let us educate newcomers at Wikipedia about what Commons/Wikidata is, and gently introduce them to those projects. If they're to evolve to experienced contributors, they'd have to use those projects anyway (for adding images, and on some project,s infoboxes), so the impact could be higher than the numbers suggest, as many users could make advantage of Growth features both on their Wikipedia and Commons/Wikidata.