Yes, a PWA can send push notifications, but only to people who agree to get them. On Android phones and desktop browsers, people can usually allow notifications straight from the web page. iPhones are stricter. Since iOS 16.4, a web app can only ask after someone adds it to their Home Screen, opens it from there and taps a button to subscribe. Behind the scenes, the PWA needs a service worker and a push service to deliver messages. Support still varies between browsers and devices, so test on the phones your customers use. If someone blocks notifications, that channel is closed. A wallet pass is one way around this, because it can send lock screen notifications through the wallet app already on most phones.