I still have a Pixel 5 and one of my favorite features is double pressing the power button to activate the camera. It works so well that my camera is ready to go before I have even focused on the subject. I don’t know if this feature is available on an iPhone.
On the iPhone you need to take it out of your pocket, wake up the screen by tapping it once, or lifting it to some angle that the screen turns on. Then you need to long press the on screen camera button.
If you enabled the double tap, you still need to take it out of your pocket and wake up the screen before you can double tap.
On Android you could have the camera ready before the phone is even out of your pocket.