The UNO only has 6 analog (PWM) outputs.
There exists SoftPWM implementations
Is it possible to multiplex the HW-PWM signal to 2 LED's and switch per LED? If done fast enough I might not be noticed?
When LED A goes low, LED B is switch on. Yes, there is definitely coupling as together their summed brightness cannot be 100%. but for lower brightnesses
one could repeat a pattern something like: A(on)B(off) A(off)B(on) A(off)B(off) ... might need extra HW.
just thinking out loud ..