The question about “why is the alarm 9 minutes” has had an answer for more than 50 years. It isn’t an Apple creation, but goes back to early digital alarm clocks. There are two common durations for snooze: 7 minutes and 9 minutes.
Why? People sleep through their “get up time” when snooze is 10 minutes or five minute increments as they may hit snooze more than once and in semi-sleep state people aren’t cognizant of which of the “5” or “0” decrement the clock is on. The 7 and 9 minute option give a lot of differentiation.
I asked this question in the late 70s as a kid and had a professor in human cognition and one in electrical engineering next to me that both knew pieces of the answer. Most product designers who have backgrounds in human cognition also know this understanding as well.
The best option to actually get up when snoozing is a random snooze duration between 4 and 8 minutes. Longer than 8 minutes and dream state can kick in, so disrupting that is helpful if you want to get up.