Does it work or not?
As with many things in Cambodia the answer is, it depends. If you have a foreign card linked in your apple wallet, then my experience is that it works in 75% of the places who accepts cards in Cambodia, supermarkets, bars and restaurants, the challenge is that just because it worked one day does not mean it works the next day, I found that out the hard way myself this week.
On Monday I went to Nagaworld Lobby Cafe and had a sandwich and a beer, paid with my Chinese card linked to apple wallet no issue at all, come back 2 days later and it does not work, luckily, I had the physical card with me as backup otherwise I would be in trouble.
So in conclusion yes apple pay works most of the time but make sure you have a backup in case it doesn't