The hardware being ready it was matter of selecting the software that would bridge the gap between my phone and remote computer.

As mentioned before, the OS limit on the iPhone 6 restricted what could be installed, however two complementary applications fitted the project perfectly and were available for iOS 12 (albeit older versions):

• WireGuard: well integrated VPN app that automatically switches on when the local network is left, making home or remote work a seamless experience, while guaranteeing a secure connection.
• Termius: the terminal, an excellent and well polished app, allowing to SSH to the remote workstation.

Both of these applications were free, or had a free tier, and worked as expected.

Having an SSH tunnel to a remote computer, whatever it is (in my case my headless Raspberry Pi) opens all the possibilities as long as there is an available network.

Thanks to the smartphone the SSH connection could go over WiFi or 4G seamlessly and having all components with batteries allows in-field operations.