Even with the cost of a $5 ethernet adapter, you can get Android phones significantly cheaper than a Raspberry Pi.
GPIO is a bit trickier, since most devices don't break it out, but for some purposes the audio jack is usable. There's also USB-GPIO adapters but they can be a bit pricey (although if you're interfacing with something like an ESP32 BLE works really well)
GPIO is a bit trickier, since most devices don't break it out, but for some purposes the audio jack is usable. There's also USB-GPIO adapters but they can be a bit pricey (although if you're interfacing with something like an ESP32 BLE works really well)