Recording keynote presentation: how to add video in addition to audio

Keynote's new "record presentation" is terrific, especially now with conferences asking for pre-recorded talks. I like the following features:

• It lets you see the "presenter view" with the next slide beside the current slide while recording.
• It allows incremental recording: you can easily stop the recording, rewind, and re-record the last bit.
• It lets you edit the slides and keep the audio: for example, if you find a typo in the first slide, you don't need to record the whole thing again, just correct the typo and re-create the movie of the recording.
• It's fast, doesn't require wifi, etc.

The only missing feature is that this is only audio and not video: I would like the movie of my presentation to have a small box showing me talking like you see on zoom. It would be great if I could use my laptop's webcam to add this. Is it possible?

Thanks!