This is done like that last May. (P3, from 4K video)
They can look a little like an over sharpened JPG but quite acceptable quality.
Definitely best to take stills as RAW but it is a pain to stop video and stop moving to take them - and wait 2 or 3 seconds while the large file writes to card.

 

This is a RAW file with quite basic Lightroom conversion.
Definitely better but not astonishingly so. (both clickable)