At the moment Safari on iOS doesn’t support web push notifications.
web-notifications
How to send a web notification at a specific time
You can use the Push API to send timely notifications from your website (the notifications are delivered even when the user is not on your website). If you use Pushpad, a service for web push notifications, it is very simple to set the time when the notification must be delivered.
Reset browser permission for web push notifications
Many issues related to web push notifications can be solved by simply resetting the browser permission. That removes the old browser subscription and creates a new subscription.
Can I use SVG images inside Web Push Notifications?
A customer has recently asked if they could use SVG images as the notification icon. Unfortunately the answer is no at the moment because of browser support.