I spent a lot of time researching this - I'm the bellend who decided he *had* to have retina-searing, colour-changing LED strips under all his pedalboards.
The ones I use are 12V RGB, so easy to power from a decent Pedalboard PSU (reverse polarity for extra fun!) but they need a lot of mA compared to pedals - approx 1.2A per metre.
https://learn.adafruit.com/rgb-led-strips/current-draw
If you only want one colour, the draw is about a third of that and the PSU will probably handle it but you'll need to do the maths!
You can run them at 9V, they just won't be cornea-scorchingly bright, which would be a shame.