Thank you so much for pointing this out to me! That saved me a lot of trouble!
I had to look up the SPI and PCM devices, which brought me here:
At the bottom of that page it says pretty much what you two said.
To control the LEDs you can use either PWM or PCM or SPI.
When I started this thread I didn't know these options, because all the tutorials I read only mentioned PWM to control LED panels.
So - once again - the Pi is a swiss army knife!
I consider my questions answered and will have to try it out now