Hi, I know I lack reviews, as I am new here- but I have extensive skills and experience in networking, blockchain (having spent a year running a mid-sized mining operation and mining pool, as well as a being a user of bitcoin since nearly its inception) and in fact, Home Automation as well (having installed complex systems in my own home and several other friends homes, all using mixed environment technologies and standers- and I can assure you I can complete the job to any degree you require.
You stated you just wanted a diagram & instructions of how to complete this? I can complete that in a couple hours and use advanced tools to make it as clear as possible, along with written instruction.
Finally, there is no singular blockchain. For instance, most cryptocurrencies use their own, completely independent blockchain. ERC20 tokens all use Ethereum's blockchain- and an ERC20 token would likely be the easiest to implement, and still be stored publicly. Unless you are speaking of implementing bitcoin as a payment method for customers (which I could also accomplish).
Your only other options would be to create your own "Cryptocurrency" (which would only be a token for data publication, with no real value) along with its own blockchain to store data. Not a task as simple as an ERC20 token, but by modifying existing code, it could be accomplished in a reasonable time frame.
My work would just be for instruction and diagramming. For me to complete the task would be more expensive