Somebody with more knowledge will come along, but it’s not only the processing power that is required, but I believe there are specific interactions between the Roon OS and the hardware.
You could, most likely, buy the PC you linked to, and run Roon under windows.
The intent of my original post was to have thread about what was the best “used/previously loved” machine to run Roon OS.
Simply, Roon OS occupies a whole machine, nothing else can run on the machine. Roon is an application that runs under Windows, Linux & MacOs.