Apple declined to implement 16 Web APIs in Safari due to privacy concerns

At least one of the API's listed (requestIdleCallback) is available behind the Experimental Features switch in Safari on iOS13.5

Apple seem to take a more cautious approach but it would be good to see some more of those API's available in Safari

We don't need a battery API but understanding whether a device is in low power mode would be useful

I'm really excited about the new permissions model that Apple is using. Perhaps in time -- after some testing -- they will gradually enable these APIs, as they are quite useful.

The listed "Idle Detection" is a different spec that is way more invasive than requestIdleCallback (which seems on track to be deployed more generally in Safari).

It's about detecting user idleness, including in the case the user has another tab active, not a way to queue and coalesce bits of work at an "idle" moment to optimise for latency and battery life.

The Idle Detection spec at https://github.com/WICG/idle-detection says it itself:

"As opposed to the requestIdleCallback, this is not about asynchronously scheduling work when the system is idle."