Magento – Create an extension in Magento for Web push Notifications

I want to create an extension with web push notification in Magento. Purpose of this extension is to send notification on customer system even web site is not open.
I wanna to create an extension to add notification functionality like this site is providing

https://www.izooto.com

I am using the Google service worker for implementation.

We want to create functionality like Facebook or any other eCommerce site that send notification on user system even site not open.
I am not aware how we can send notification on each event like customer purchased an item or notification on customer login.

Please suggest how we can initiate this extension.I have integrated with help of this link:

https://developers.google.com/web/updates/2015/03/push-notifications-on-the-open-web?hl=en

I did lot of R&D on it and implemented basic example to send notification but how I can make notification data dynamic
Any help will be appreciated.