JAMStack isn't much of an option for services that can't trust the clients and cannot rely on high latency consensus algorithms.
It's also brutal for battery life.
JAMStack != static site served entirely by a CDN. There’s an A for API in there. Where’s the A for IPFS? There’s no such thing.
It can be built, but I don't think there are any frameworks that make it easy. A JSON file can be an API, but authentication and encryption using static publicly available files is more challenging, especially for a large number of users. That is where blockchain solutions come into place.