Hello KRB, welcome to Microsoft Q&A forum.
It seems like you're misunderstanding the Xbox app with the Xbox console. Your purchase is correct for PC.
The "Xbox app" is just a Windows PC application that manages Microsoft Store games on your laptop. The Xbox console is the physical gaming device (like PS5 or Switch) – which you want to avoid.
You'll need to install the Xbox app (free from Microsoft Store) on your son's laptop to install Minecraft for Windows (Bedrock Edition). Once that's done, you can launch both Java and Bedrock editions from the Minecraft Launcher. The Xbox app is just how Microsoft Store games are delivered on Windows – your son will be playing on the laptop, not a console.
Let me know if you need any clarification.