Plug the NeoPixel strip into the 3-pin JST connector marked D3 as shown here.

Turn on the PyGamer and the game will start. Once you get past the loading screens, the NeoPixels will light up.

Double Blasters

Despite being listed in the NeoPixel strip pin list, the D2 JST plug can't be used in MakeCode Arcade at the moment. However, there's another way to use double Vibranium Gauntlet blaster strips! Since NeoPixels can run in parallel, a DIY wire y-splice will do the trick. See this guide for more on wire splicing.

Here, the ground, 3.3V and data pins from the D3 JST port have been spliced to two adapter cables.

By plugging in a pair of strips to the adapter, you get twice the NeoPixel action! They will run identically to each other, which works well in this case.