To be honest even PGP signing has some issues: it's not clear what does it mean to sign a commit and there is plenty of misuse of that (see [0], `git push --signed` solves some of these issues).
Git patch workflow doesn't support signed commits and some kernel devs explore alternative ways of signing [1].
Git patch workflow doesn't support signed commits and some kernel devs explore alternative ways of signing [1].
[0]: https://mikegerwitz.com/2012/05/a-git-horror-story-repositor...
[1]: https://people.kernel.org/monsieuricon/introducing-b4-and-pa...
By "keybase providing alternative" do you mean that they have hosted, encrypted git repos?