[auxym]

Unless he has a specific interest/project in mind already, I'd look into something like this to start with:

https://www.sparkfun.com/products/18577

It's from sparkfun so you generally get better support and docs than a random box of stuff from Aliexpress. The QWIIC ecosystem means that you can daisy chain a whole bunch of sensors easily and without soldering. It includes a small but nice selection of sensors, actuators, buttons and LEDs to play with and some suggestion projects.

Soldering and more advanced stuff can come a bit later if he gets into it. No need to discourage a kid from learning electronics because soldering is hard and you want to save 5$ by buying a bare IC instead of a breakout board (not to mention that the current shortage means that breakouts are often more easily available to hobbyists compared to bare chips).

[fckthisguy]

Plus one for QWIIC. Choosing an ecosystem that's easy to buy (not always sold out) and cheap can make a big difference.