Hi @NoCodeJedi ,
The business use case is to send push notifications to all users regardless of their actions in the app. You can use this as a way to send the same message to everybody such as a product announcement, a new app version, or simply get them back to the app. This is what I did.
Main app (Dear Cloud), this is the app my users use.
Admin app (Dear Cloud Admin), this is where I manage my push notification campaigns and send them. Since the Admin app shares the same DB than the regular app, it can send notifications to my users.
This is how it is done in the Admin app.
1- I added a “Campaigns” tab where I draft the notifications I want to use to all my users.
2- Once a new campaign is created and I am comfortable with its text, I click on “Send” to send it to all my users. This is where the magic happens.
In this modal screen, I have a “hidden” list on my Users tables. Since the Admin app points to the shared DB, these Users are my actual customers I want to reach out to.
In this same group, I also put a countdown component.
Once its time is up (I put 5 seconds), a couple of actions are triggered:
First, since I am on a list of Users, I simply use the out-of-the-box Push Notification action on the current User (email) and add the current campaign text as its body.
For cosmetics (optional), I also update the current Campaign’s total send (send = send + 1) so that the progress bar follows along.
As someone mentioned earlier during the conversation, this solution won’t probably scale to 10k+ users but in my case (I don’t have a lot of users right now), it is a great band-aid solution before we get Adalo fully on Firebase.
Hope this helps
… but for me, this is immediately useful right away!!! I tried to do something similar a few weeks ago, but it was getting tricky and now your info helps put things into better context! Many thanks 
your solution makes perfect sense as a email campaign solution. I thought you had figured how to send in app notifications from an different app sharing the same DB 