To be fair - building a business like Helm while needing to deal with other people's hardware and their software updates which you wouldn't find out broke your product until your customers start screaming about their email not working - wouldn't be fun. I could easily see how someone could want to do that and seriously consider it, then discard it as an option (or at least as part of their MVP launch options).
So make a supported hardware list,docker container, etc. The hardware is interesting, but the types of people who would buy this either already have racks in their houses and just want someone else to manage their stuff, or want to manage their own hardware because they want to make sure they have their own hardware components locked down. It's a neat project to be sure, and it's not terribly expensive for the hardware, but the real money maker is the ongoing support and security for the service, which is functionally really similar to a cloud service without a lot of the benefits.