I have been waiting for this for a long time. I run a small forum and have maybe 10 core users who use it a lot. It is a recreation of a forgotten kind of old forum but with some modern features. I would like users to be able to opt-in to push notifications when someone replies to their post or when they get a private message. I get Patreon support that breaks even for server fees but otherwise it is a labor of love. I am currently using a Telegram bot to send users pushes but I was always hoping Safari would finally relent so I could use the real deal. Thank you, browser vendors. I agree with most of the comments here that push messages are generally evil but this is a huge boon for small niche websites like mine that don't have the resources to make a dedicated app.