This is a plugin that existed for Kirby 2 and was updated for Kirby 3: Kirby Git Plugin for Kirby 3 (gcapc)
And here is a fork of the one @wottpal created a year ago but which stopped working after the release of Kirby 3, so @flupe supposedly fixed it: https://github.com/flupe/kirby-git (I have never tested this so can’t tell).
As regards Kirby revisions: There is no version for Kirby 3 that I know of.