We keep thinking about ways to combine iroh + zeroMQ! I think these two could compose. (Not familiar with nanomsg myself)

About tailscale: It's similar, but iroh is not a VPN, so it doesn't add a TUN interface. Instead, you'd build iroh directly into your application. Using iroh you can build a VPN, and there are projects that do so (iroh-lan/iroh-vpn are some hobbyist projects). The upside of building it into your application is that it doesn't need special permissions and is easy to ship to the user.