> I think in many cases the authors value functionality much more then esthetics.

In many cases the repository isn't meant to be more than for source code too, not everyone use their git repository as also the marketing page, that'd go somewhere else.

With that said, grapheneos.org doesn't seem to have any screenshots either, which I also don't understand and think is a bummer. Even though the point of the differences with GrapheneOS might not be mainly visual, just showing what it looks like seem like a no-brainer.