They sell servers, but as a finished product. Not as a cobbled together mess of third party stuff where the vendor keeps shrugging if there is an integration problem. They integrated it. It comes with all the features they expect you to want if you wanted to build your own cloud.
Also, they wrote the software. And it's all open source. So no "sorry but the third party vendor dropped support for the bios". You get the source code. Even if Oxide goes bust, you can still salvage things in a pinch.
Ironically this looks like the realization of Richard Stallman's dream where users can help each other if something doesn't work.