The Wikidata software is extensions to Mediawiki (which is maintained by WMF), and though the extensions are primarily developed by a Wikimedia chapter (Wikimedia Deutschland), it's disingenuous to say that Wikidata is fully maintained by them. Its operations, at the very least, are maintained by WMF, and quite a bit of development and a large amount of code review was done by WMF.

Similarly, the test/dev for Wikidata is part of Wikimedia Cloud services (which I created). That environment is also WMF run.