There is a Holochain app on mobile phones.
Shipping this fall, Volla Phone’s new Quintus model will have two Holochain apps preloaded on it. One of these is Relay. On its face, Relay is a simple chat app. But its impact is much deeper than that. Like Signal, Relay is fully encrypted. But unlike the industry standard for secure communication, Relay doesn’t use central servers, adding an additional layer of security and privacy. Relay also doesn’t need your phone number as it addresses its messages directly to your public key which acts as a decentralized digital identifier. Not only does Relay come preinstalled on the Quintus, but it will also be available for Windows, MacOS, Linux, and all Volla devices including the Volla Tablet
Read Article: https://blog.holochain.org/happs-spotlight-relay/