I’m currently using Graphene and I love it. There are some features in this OS that i have never seen before. It feels like I’m just running a regular OS. I don’t notice anything unusual.
One thing I really like with gOS is the ability to remove network permission on apps. I use Gboard with no network, and I have found it so far to be the best keyboard for me.
The TLDR is that it’s a new wifi standard/generation. It means WiFi 6. It’s not entirely important, but some phones display that to show you that you’re using fairly recent technology.