Also in the response structure sitematrix.NN.code I think the NN key is arbitrary and unnecessary, so in formatversion=2 it could just be sitematrix.code

formatversion=2 can address T100459: SiteMatrix API has two fields called "code", which is confusing. See also T113034: RFC: Overhaul Interwiki map, unify with Sites and WikiMap.

@Spage: Those changes sound like they're well beyond what can sensibly be done with formatversion=2.

formatversion is about formatting the same data in a different way, not drastically altering the data structure. The latter is the same mistake Wikibase made that resulted in T95168: [Task] Remove calls to getIsRawMode() in Wikibase, and calls to setRawMode() in tests taking a long time.

Seems to work as expected.

https://meta.wikimedia.org/w/api.php?action=sitematrix&formatversion=2

"closed": true