Agree, beans and grinder first the rest is just how your going to get the water through the ground beans which is going to offer the least if its all espresso.
If I think about all the variables I’ve been able to play with the most I’ve noticed a difference with (be it a small one) it’s temperature (but between 3 or 4 degrees at least), flow then preinfusion. I honestly don’t think I could tell the difference between 2 shots that were flow controlled and preinfused or not!! 🤔