It appears that Apple may be working on adding service workers support to WebKit. The WebKit Feature Status webpage has recently been changed from "Under Consideration" to "In Development." This change may be an indication that Apple will eventually support Progressive web apps (PWAs).
This is part two of a two-part article covering the current state of Web search APIs. This article takes a look at the Web search tools/APIs provided by Google and Microsoft. Article includes comparison charts highlighting some of the key differences between Google and Microsoft search tools/APIs.