Most likely he doesn't use GPIO, if it's just a tailscale/pi-hole client or something like that.

If you REALLY need GPIO then just add a USB-C OTG MCU board like a ESP32, or even the ancient Arduino Uno works as USB GPIO via serial TTY on Android.

Or just use a ESP32 by itself, if you don't need a full Linux OS, just to toggle some GPIO pins via the internet.

Possibilities are endless. Just use your imagination, or ask some LLM.