I don't know if a peer-to-peer resource trading market and currency are necessary here; the device owner with spare capacity and the business proprietor may be

I don't know if a peer-to-peer resource trading market and currency are necessary here; the device owner with spare capacity and the business proprietor may be one and the same person, which would simplify the situation a great deal. You have a cafe/small business owner who already owns a smartphone: that device has a decent chunk of data plan allowance, CPU and memory. They'd like a small site to promote their business online; so they install the web server app and it allows them to add, edit and publish basic content - a few images, some blog posts, etc. Self-hosting like this means they don't have to sign up for a monthly subscription, their users aren't subject to any tracking (assuming there's none embedded in the content generated by the app), and service provision scales until they need to upgrade to a dedicated host. The questions about radio and battery usage are totally valid, so perhaps those need more consideration (user superkuh has some suggestions there). In short: the resources and capacity already exist and we've already paid for them. The question is whether we can re-use those rather than being sold more of the same.