Well, from those two hours you have to subtract half an hour for emoji presentations and another half hour for uplifting 'one of every colour' videos.
Apple Watch - Series 4 - 30 minutes
iPhone - 3 versions - 45 minutes to an hour
Airpower and AirPods with "Hey Siri" announced - 10 minutes
I'm still hoping for at least iPad Pro's but we will see.