Simple Web Push Notification ( One Signal, Firebase etc )

Requirements:
- With OneSignal, Firebase etc ( Please advise before confirmation ).
- Clean and minimal code
- Must be purely in Javascript and frontend
- Native browser UI
- Ability to collect Web Push Subscriber when user tap on “Allow”
- Ability to redirect user to another page with javascript function when user tap on "Allow"
- Ability to redirect user to another page with javascript function when user tap on “blocked”
- Check whether Push Notification is doable for the current browser and set conditional
- Other things that necessary

Final Outcome
- Clean and Minimal javascript code that is easily integrated into any html landing pages.
- Able to collect Web Push Notification
- Able to send Web Push Notification to Subscribers
- Including the requirements of above

Please download attachment to see examples and visual UI.