@PalejaS Thanks for reaching out to Microsoft Q&A,apologize for any inconvenience caused on this.
I understand that you are looking for a tutorial to host your flask application on azure app service. If my understanding correct you can go through the below tutorials.
- Deploy python on App service.
- flask app + PostgreSQL on App Service.
- Python developers tutorials on Azure.
The above tutorial can help you on how to deploy flask application to azure app service.
If your app service want to connect to firebase you can implement these instructions in your code that are mentioned here in this firebase database documentation.
Hope this helps, let me know if you have any further questions on this.