I like how people come up with new uses cases for headless Chrome. But for his use case ('presentation') there are tons of presentation libs/franeworks in HTML/JS/CSS which support code embeddings with syntax highlighting. Same quality but much easier workflow since code stays editable.
You assume he uses HTML/JS/CSS for presentation. What if it's Keynote/Powerpoint?
If he presents code then a HTML/CSS/JS system should be prefered aince syntax highlighting is easier. Something you can't get automatically done with the alternatives you mentioned.