Implementing pull sync on SwiftUI app

I have a master DB in Atlas, and RealmDB on SwiftUI app. I would like to implement an “on-demand” pull sync from the Atlas DB to mobile RealmDB. My understanding is that Realm Sync is FULL sync only. Is my best approach to implement the pull manually and just update the realm DB from the pull from Mongo Atlas DB?

Ok, I see that accessing Mongo Atlas directly via mongo-swift-driver is not supported on iOS, since it targets only macOS and Linux. If the only way to access Atlas from iOS is through Mongo Realm, is it possible to only pull docs on demand to Realm?