We live in a tenant where we have over 25 different companies. When it comes to customizing and supporting the tenant catalog is too broad, but the site collection catalog adds support nightmares with syncing and managing the apps and installs in each one. It would be great if the site collection admin could choose an additional Site Collection app catalog to pull from. This would allow for us to manage company specific apps in a Company site collection catalog much like the tenant catalog while still getting site specific catalog items from the site collection catalog. In this model, there would be three levels a site admin could get apps from, Tenant app catalog, local Site Collection App catalog and this new configurable remote site collection app catalog.