It's unfair to compare an idling deep sleep device with a cold boot.
However, there is a shortcut: Just don't boot a full OS (thinking of custom firmware which boots in fractions of seconds, standard in the Microcontroller world). Or boot an optimized Linux user space. I am confident with a bit fiddling one can bring down a standard SBC Linux to a few seconds from cold to ready.
Functional comparisons among devices within a category are always fair. Pointing out a device’s perceived shortcomings is not an attack on the people that made it. One crucial role designers play (ideally) in product development is seeking out honest feedback, filtering it, and figuring out if that feedback can help make the product better for end users. The FOSS landscape needs a lot more of that.
> Functional comparisons among devices within a category are always fair
When they have the same prerequisites, yes. But then you need to count in the time the iPhone needs to boot as well, which will probably mean you are at a similar range.
Ok, now read the other three sentences that explain why I said that.
You turn a dedicated camera on as you grab it, cold boot, and most of them will be functional before you manage to put your eye to the visor.
>It's unfair to compare an idling deep sleep device with a cold boot.
Sure. My Fuji X100 is ready to shoot in about a second after a battery swap.