I received the RW 22.214.171.124 app upgrade and Google came out with a couple of patches for Oreo, so I went ahead and upgraded my Pixel phone. Everything works just fine, both RW calling and messaging, and also the new features and changes to android.
I am, however, noticing a little cell data usage even when I am solidly connected to WiFi. It appears to be about one Meg per day. Before Oreo, I was definitely using less cell data. It’s not a lot, but it is measurable.