You are very welcome to create your own Notification extension. You can publish it on WordPress.org repository. See below the detailed guidelines to how to make it the best extension ever written.
For your convenience, we created extension boilerplate. You will find it on GitHub:
With such a boilerplate you can be sure to follow our standards but most importantly – you can start your extension blazing fast.
We are following specific naming convention which is: Notification : Something.
The namespace should follow the general format which is: BracketSpace/Notification/Something.
The Something is the part where you place your extension’s name.
If your plugin is free and released on WordPress.org you can let us know about your awesome work. After review we will place your plugin in the Notification’s Extension Directory!