The first attempt to deploy the WikibaseMediaInfo extension failed due to T211237: wbgetentities has stopped returning content on Beta Cluster Commons. The cause for this is still unclear.
One hypothesis was that federation support is still incomplete, see T204748: Create Federated Wikibase instance on Beta Commons. Specifically, the hypothesis was that the WikibaseClient configuration (which has the empty ID prefix refer to Wikidata) conflicts with the WikibaseRepo configuration (which has the empty ID prefix refer to Commons). This however turned out to be untrue: WikibaseClient and WikibaseRepo currently do not share state or configuration. This is conceptually problematic and may lead to issues at some point (see T211800), but for now it means that inconsistent WikibaseClient and WikibaseRepo configurations can in fact co-exist: It's possible to run MediaInfo on a wiki that at the same time acceses another Wikibase repo (like Wikidata) from Wikidata, with a configuration like that on the beta cluster (confirmed locally by Daniel).
This ticket is intended to track the investigation and resolution of any issues that block the deployment of MediaInfo on a fedarated Wikibase environment as targeted by the SDC project.