I have never seen this before and am excited to learn how this was accomplished.
How can I record a website demo as an animated SVG like this?
I found https://github.com/marionebl/svg-term-cli, but that seems to be limited to terminal sessions rather than browsers.
I spent a month looking for the answer.
Finally I decided I should just ask them.
They answered right away.
So, it sounds like there isn't an automated way. Just hard work.