The Pixie's look like they'll do the job nicely ! USD 15 a pop... (ouch)
OP, organise the (hard part) mounting, comms and code - and you're there.
The nice thing here is that they have a gamma-corrected PWM driver on-board, so nothing else to think about at that level.
Depending on the distance between LEDs and strings, you may look at RS485 for the 2-wire interface at high speeds.