I keep wanting Tailscale to offer a "tailnet API" whereby you can bundle a tailnet into your app, and users can connect to other instances of the app (whether their same account or other people sharing parts of their app/data) seamlessly: E2E encrypted, NAT busting, it just works.

Think about it: mobile and desktop apps no longer have to upload things to some third-party service to share with yourself or a group of people. You could set up your own server of course but that requires technical expertise. The mass market could share data, sync, and communicate, straight from their devices, without any service hosting their data. It's just all on the private network.

There's probably a billion-dollar market there (or more) if someone can figure that out for a lay audience: virtually unlimited, encrypted private networks on-demand that require no setup.