A nice clean chain and pulley wheels really help the drivetrain. It has often entered my mind that bike components should be engineering for easy cleaning to promote life and performance.
I had noticed in the past that some groups are easier to clean than others. Was it because they were trying to remove materials that makes them light but also sparse and accessible? Duraace 9100 rear derailleur is a great example, super easy to clean.
Notably with SRAMS latest eTap derailleurs you should be aware that the rear pulley wheel is quite terrible to clean.
The Guide pulley (the one higher up) is less accessible on one side, has less space between the body and pulley. Meaning it hides dirt easy and also harder to clean. I use a little screwdriver, while manually spinning the pulley wheel to collect the crud.
This is best performed with the rear wheel off.