WS2812b Arduino fade 10 led pixels on and stay on, half a second later fade another 10 led pixels on and stay on, half a second later (maybe delay(500); fade another 10 leds on. all while each droup of the 10 leds that were faded on stay on while the other groups of 10 leds fade on.
Your post seems strange. Do you have a question for the forum?
Am I right in thinking that only one thing changes at any one time?
If so just write the code that does the change, do them one at a time.
We don’t write code for you but we will help. So start at the first step, if you have trouble post all the code and say what is happening and what you want to happen.