The accompanying blog post [1] mentions the Arduino Nano RP2040 Connect [2], which includes "a highly efficient power section, a powerful WiFi/Bluetooth module, and the ECC608 crypto chip, enabling anybody to create secure IoT applications with this new microcontroller". It also looks quite small.

[1] https://www.raspberrypi.org/blog/raspberry-pi-silicon-pico-n... [2] https://blog.arduino.cc/2021/01/20/welcome-raspberry-pi-to-t...