My questions is do 12V strips with individually addressable LEDs exist or are they just for what ever reason not a thing?
They are not a thing.
This is because to get to 12V for the supply you need to have three LEDs in seriese and that means all three are all going to do the same thing. There is no point in burning off that power doing just one LED as you only need 5V for one, even so you have to burn off the excess between than and what the LEDs need.