Lawnchair has been around for many years. Not sure why it's still called "early access" or showing so few downloads, unless this is some sort of relaunch of the project.
I last tried it a few years ago and it was indeed a "Nova killer", but not in a good way: somehow it managed to mess up some settings so that some features of Nova no longer worked the way they did before I tried it (how I don't know: it shouldn't be able to corrupt Nova's data, so it must have messed-up something in the system itself, only that also shouldn't have been possible). Can't remember the details as it was some time ago, probably on my previous phone, certainly before Nova 7, but I've never wanted to try it again.
Mind you this thread prompted me to search on "Launcher" in the Play Store and having not done that for a few years it was a bit depressing: it felt like there had been very little innovation or development in the years since I last looked.