@Observable observation outside of SwiftUI

I've just started tinkering with @Observable and have run into a question... What is the best practice for observing an Observable object outside of SwiftUI? For example:

@Observable
class CountingService {
    public var count: Int = 0
}

@Observable
class ObservableViewModel {
    public var service: CountingService

    init(service: CountingService) {
        self.service = service
        
        // how to bind to value changes on service? 
    }

    // suggestion I've seen that doesn't smell right
    func checkCount() {
        _ = withObservationTracking {
            service.count
        } onChange: {
            DispatchQueue.main.async {
                print("count: \(service.count)")
                checkCount()
            }
        }
    }
}

Historically using ObservableObject I'd have used Combine to monitor changes to service. That doesn't seem possible with @Observable and I don't know that I've come across an accepted / elegant solution? Perhaps there isn't one? There's no particular reason that CountingService has to be @Observable -- it's just nice and clean.

Any suggestions would be appreciated!