In SERVER-58220, we considered creating a new method NamespaceString::isShardLocalNamespace() to determine whether or not a namespace exists locally and independently on each shard. The work was put off for a more targeted approach.

This ticket is to track a broader approach. We should consider generalizing the concept of a shard-local collection. This work should be coordinated with Sharding EMEA to ensure representations in the code are consistent.