alt Hacker NewsIt's not really hard at all, calculate the max power the leds will draw and get a psu that'll never exceed 90% of that. Your average usage will be waaay lower anyways since you don't usually show all white.
5v power supplies are easily available, Meanwell is a popular & reputable brand. The same psu can run your lights and microcontroller.
Fully lit, these would be blindingly bright, and would need tens of amps of power supply (source: I have a strip of 100 WS2813s (I think, anyway the 12V ones) and the 3A supply I have would be fully loaded if they were all on full bright white. These suckers are bright).
However, you can always just limit it in software. Total "brightness budget" for the display, scale everything to dimmer if exceeded.