comments:
I would not recommend using a solderless breadboard except perhaps in testing. Perforated prototyping board, aka perfboard or protoboard (example) is going to be a lot more reliable especially for a kid's toy, although you're probably not going to need very much of it for a project like this. Re powering this project - here there be a few small dragons. The pico uses 3.3V but has a voltage regulator that is rated to tolerate 5V. Most neopixels will work at 3.3V but generally prefer 5V. Off the shelf USB power banks deliver 5V, so if you design the rig to run on 5V you can avoid having to roll your own power supply. The main gotcha with that: If you run the neopixels at 5V, you will usually need to use a logic level shifter to allow the pico's 3.3V logic to work with them. A more efficient and compact way to power this thing would be to use a battery management board and 3.7V LiPo, but you can decide whether you want to go there or not.