iOS still has no support, and nothing even on the horizon, as far as I know. Apple is intentionally holding back the open web. I find this infuriating.
Also, the new awesome privacy settings in Safari on the beta iOS and beta iPadOS and beta macOS Bug Sur are very much appreciated, at least by me.
It absolutely IS possible to add the feature, as opt-in like with app permissions, and e.g. with some user-initiated event like audio already does.
The REAL motivation here is money, forcing users to use the appstore, instead of the web which is an open protocol.
Nagging will always be good business, no matter what platform or what shape or form.
Please tell me the beta community is calling it that.
Aside from the shabby technological issues involved, the applications themselves these pseudo OS features are put to generally are opposed to some of the things I value highly: privacy and stability, for example. Most applications don't need a social component or to harass me to re-engage, to utilize hardware or other software services on my device, or even to export/share data with other applications.
As far as the technology itself: the platform is generally a terrible technology for even the dubious purposes it is usually put. It's clunky, and even with things like wasm the development story for the platform is, at best, terrible. Also, in my experience, the quality of development in the web sphere is generally (not always) poor compared to similarly complex projects in other areas/applications.
Also, Apple's stubborn insistence on lock-in (and lock-out) is really annoying if many of your contacts are not on Apple platforms.
There are clearly trade-offs, and there is a lot of valid criticism of the Web, but I'm really glad that the Web exists as a sort of operating system that guarantees some freedoms that native platforms are increasingly taking away from us (although not all of them are as paternalistic as Apple).