It is standardized and Safari isn’t the first. Edge already supports this on Windows, Chrome does everywhere, and they’re all using the same “manifest.json” dec

It is standardized and Safari isn’t the first. Edge already supports this on Windows, Chrome does everywhere, and they’re all using the same “manifest.json” declaration whenever display is set to “standalone”. These all require a service worker, so that’s the destination of your pack and, conveniently, a cache for downloaded assets.