Firebase Realtime Database

Which option do you prefer to go with (considering scalability, and a limited budget):

Technologies in use: Angular / .NET Core 6

What do we want to achieve?

We want to create simple near-time web notifications, those notifications can be categorized into 2 sections:

• User notification: which represents user activities and engagements.

• System notification e.g release notes and maintenance time. The notification object is too simple just a title, body, userId, notificationStatus, and readAt. notification status is an enum with 3 values: unread, menuOpened, Read.

Options:

1. use Firebase Realtime Database for user notifications and Microsoft SQL Server for system notifications (maybe using long poling or so to frequently call the getSystemNotification API ).

2. use SignalR to push new notifications along with the SqlServer database and store both user and system into one table (as they almost have the same attributes)

We are building a social media app, where users will post images, like their post, and make friends based on their interest. We are currently using Cloud Firestore and Firebase Realtime Database. We are looking for another database like Amazon DynamoDB; how much this decision can be efficient in terms of pricing and overhead?