One of the things I missed most in Google Slides was the ability to narrate information in Slides. I figured that Google really dropped the ball there! Although I am not a big PowerPointer, the few times I do use it all include voice narration.
Fortunately, some super brains around have come up with work-arounds! One is the create your slide show in Google Slides and then import it into an app called Movenote. You can then embed it into your webpage if you wish.
Another work-around is the create your slide show in Google Slides, download each page to your device. Then open and log in to an app called WeVideo and upload your slides as images. Record your narration for each slide and then share it!
Movenote is much easier to learn in a hurry than WeVideo, but it also doesn't do as much. I like to offer both to students (and teachers) and let them choose which one they are more comfortable using. A great way to differentiate your technology. You can find both apps in the Chrome web store.