Aha – wait until your Tesla gets hacked… 
Other options may come. For now, it is a regular computer. But I wrote about how I configured a NUC to work as simply and reliably as a 1970s FM radio: it contains its own storage (SSD) so it doesn’t require a NAS, it has a network or USB connection to the audio system (or wifi if you prefer), no screen or keyboard or mouse, and when you turn it on it automatically starts a Roon server. I always leave it on (draws 20 W). It has built-in Windows anti-malware. The NUC is smaller than a stack of 5 CD jewel cases, very neat.
(Ok, setting it up was a bit complex, as you can see in my description, but following the description is easier than making it up. And maybe some day somebody will sell a pre-configured box like that.)