Does he mean complex or risky (big chance of frying something)?
Not really, just that it'll probably require some soldering to connect the wires if using the shim. However it can be done without too much trouble...
In fact with one of the new builds of Espruino from Git and some minor tweaks, you can update the ESP8266 using just the Pico board - see @Ingmar_Guillaume's post a few after that too - you need to tweak the firmware updater to get it reliable.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Not really, just that it'll probably require some soldering to connect the wires if using the shim. However it can be done without too much trouble...
In fact with one of the new builds of Espruino from Git and some minor tweaks, you can update the ESP8266 using just the Pico board - see @Ingmar_Guillaume's post a few after that too - you need to tweak the firmware updater to get it reliable.