I completed this lamp 2 weeks ago. Finally I didn't use a 220V -> 5V converter, but an external power supply (an old 5V / 0.6A from a broken Philips Hue lamp)

Everything else is as I expected. I didn't take pictures during the building, but here how it is once completed : 

It works well. The RGB shield is not very powerful, so it's just enough for a night light. As it is very easy to use, I think it's a good use for this shield.

For the program, I didn't use the standard Adafruit lib for RGB : it doesn't work with my D1 mini (I had a lot of problem with that on some other projects)

Use instead NeoPixelBus lib, and output D4