In my experience this might very well be sufficient. I have a baby monitor (eufy spaceview) that does just that, and as long as you can set a volume threshold to account for expected noise (e.g. a white noise device) I doubt an ML-powered version will add much value for this use case.

I also have an eufy Indoor Security Cam, which does some more intelligent audio processing, such as detecting when someone is crying, and is able to send notifications based on those alerts. It has worked flawlessly in my experience, but also hasn't provided additional value over the baby monitor that only detects noise over a certain volume.

In the end it doesn't really matter what kind of excessive noise you're hearing from your baby's room. If its loud enough to trigger our baby monitor I'd like an alert even if it doesn't sound like crying.

The security camera we have also doesn't trigger an alarm (on Apple devices, besides from the notification sound), so that's another thing to take in to consideration.