@jastralfu This stuff doesn’t come particularly easy. I spent a long time getting comfortable with how all pieces fit. And that was working with it every day, professionally. So check the diagram. Layer 1 is the physical media - copper, fiber, radio. The Layer 1 protocols have to talk to the Layer 2 Data Link ’defines the format of the data on the network’ Layer. In other words the Ethernet frame. The WiFi Layer 1 protocols have map the data from their data format into the Ethernet frame at Layer 2 so the data can keep moving. That the interface happens at Layer 2 does not mean WiFi itself is at Layer 2.
And OP, just find a BluSound Node. Best money ever spent. It's a no-regrets buy.