Power Loss/Drain problems

A simple FET switch might be all thats needed to turn off the juice to the Neopixel hogs or a relay as indicated in post #2 What about using a pin on the Espruino to control a Buck step-up converter that would supply the 5V? hummmmmm . . . .

Neopixel shall be connected with ground first, i.e. a simple FET wouldn't be a good solution. Get a high rail FET, e.g. MIC94060 or something else with an internal charge pump.