There are a surprising number of Linux thing running webstuff likely hacked together and shipped. I find a lot of vending machine computers on eBay that boot Ubuntu or whatever and start some sort of webservice thing.

What custom software though? How does it get the data? What is it vulnerable to? What about the backend software, that's also part of the system? It's easy to say "it is hardware running software" but it obviously goes deeper than that.