> How many customers do you expect to be running on Duo for the first year of its existence? I’d be surprised if it was >0.01% for anyone.

How do you figure? Assume the average Apple cell phone replacement cycle is somewhere between 3 and 4 years. At the longer end, you’d need the sell-through rate of the Duo compared to other phones to be less than 0.04% to hit your number. We know from the Mini and other phones that Apple tends to avoid designs that it expects to have less than a 5% sell rate, two orders of magnitude higher. Even if you assume they’re aiming for 5% of dollars instead of units, and you take into account the non-Apple market (which certainly should not be unit-weighted for folks thinking about app revenue), you’re off by well over an order of magnitude.

> I have friends who dropped everything to support the Vision Pro, and I don’t think any of them felt like it was worth it in retrospect. Even the ones that got featured by Apple as a result didn’t see more than a few thousand downloads.

They should remember that they got quite a bit of social capital within Apple by doing that and hopefully they're keeping those relationships warm. But yeah Vision Pro hasn't turned out to be a big ecosystem so far.

Usually just compiling with the new SDK will get apps basic support if they have been following Apple standards.

> I have friends who dropped everything to support the Vision Pro

The VP was a niche device for a niche market. Phones are not that. I think the Duo will do very well. The one knock are the cameras do not match the Pro. I don't think will care though.

> apps that are phone only are letterboxed, but still entirely usable

How is that possible? iPhones have had varying screen sizes for more than a decade, how could any app still have a fixed size?

Apple does many crazy custom things in their own apps. Their advice is not sacrosanct. It just means you must prepare for less notice than they had if you want to compete with the frontier UI aspects that Apple apps achieve.