welcome to the forum.
First I would recommend that you should read a few examples of how to use your LoRa Hat to make a communication with a node. After that you maybe can understand a few things like the limitation of the single radio.
After that, you can read how to use a lora single channel packet forwarder. With this you can send the uplinks but you will have to work a little more to have downlinks. I don’t remember at this moment where is the example who make a gateway single channel with uplink and downlinks. The main example probably could be using the TTN. But for that probably you should ask help in that forum.
For last, try to use this solution as loraserver. Why all these steps? Because that was my experience to learn how to handle the same hat. I’m a beginner and most of the times when I skip these basic steps I have bigger problems in the future, so take the weekend to approach the challenge. The main problem with the hat is the single channel, and that is not LoRaWAN specs complain. So you must work a little bit the software to make it work.
If you’re looking to build a real solution, I suggest to use a certified concentrator to work under the specs and have a better support if you find any troubles in your design.
Hope this helps to you.