Couchbase Sync Gateway's channels are just slices through the data. The mechanism is internal to the Sync Gateway (you write a JS function that says who can see which channels and which channels a doc belongs to.) Replicating clients don't Need to know about this filtering, so channels work great with all flavors of Couch.
You could also use filtered replication but it is: a) not scalable b) not secure (the whole db would still be accessible to all users)
Couchbase has a different spin on this via "channels" though I'm not sure how it interoperates with PouchDB.