You are confusing LoRa and LoRaWAN. The RAK811 is an old but good product that can be used as a LoRa and LoRaWAN end device, and possibly as a LoRa receiver / range extender / Internet bridge (if connected to a computer for instance). I have a few projects running on RAK811, despite it being End Of Life. It is/was a good module, and I have a few of them – for which I usually write custom code. See for instance this project.
RAK2477 is a LoRaWAN-only product. And possibly EOL too. Depending on what you are looking for a concentrator could be a solution BUT anyway it doesn’t extend the range of your end devices…
First work out what you want to do, and using which transport layer: LoRa or LoRaWAN. Then you can pick your tools.