I found this discussion (linked to in the PR) more illuminating: https://www.reddit.com/r/Android/comments/7azc2i/comment/dpg...

I tried Lawnchair out when figuring out what I was going to replace Nova with. I didn't end up choosing it, but if I had known they tried to do this (even if it only made it to the alpha channel) I wouldn't have even bothered to try it out.