Apple is working on bringing web-based notifications to iOS, addressing a long-time concern of developers of web-based apps who have been unable to send notifications to users on Apple mobile devices, severely limiting the user experience and effectiveness of apps made on the web. With the first betas of iOS and iPadOS 15.4 released last week, Apple added a "Push API" toggle in the Experimental settings page for Safari, as spotted and explained by developer Maximiliano Firtman.

Link: iOS 15.4 Beta Suggests Apple to Support Push Notifications From Web-Based Apps
via http://www.macrumors.com