Design Push Notification for custom times for each device/user

• Aim : Push Notification through mobile browser. Each one of them is either a basic link to a site / youtube link.
• What’s done so far : A small collection of URLs + Title has been saved in Firebase. A simple react UI homepage where a user can submit their local time for the push notification. e.g. : I want the push notifications to come at 5 AM, some one else wants them at 7 AM or when they wake up. Basically a simple time component and submit.

I’ve looked into :

Firebase Cloud Messaging

One Signal Notification.

The problem here is it’s a common time for every push message ? I wanted to customize it per user/device.

Now :

• Is user login necessary for custom push notification, I was thinking rather than storing user credentials if it’s feasible to use a device ID of sorts?
• Should a Firebase cron job be used or a Node Script to run all the time. If so can any one of you guide me to an article or a video where they how this is done.

How do you implement this, a high level design of it ? I've no clue since I'm doing this type of problem for the first time.This is something I wanted to learn on my own, but I wasted couple days trying to come up with the design