Gnome Shell extensions can alter the behaviour of the shell. The extension Super+Tab Launcher includes all favorites in your Alt+Tab dialog to do what you want. If already running, you can switch to it, if not yet running, it will launch.
Just for your additional information, there is a way in the Ubuntu desktop to switch to the dash using the keyboard. Press Super to go to the overview. Then press Ctrl+Alt+Tab and select Dash from the pop-up. Now, you can navigate in the Dash with the arrow keys. Allegedly, this is a slow method that is hardly discoverable. You may want to turn to the extension instead.
Note in case you did not know, you can also immediately launch a favorite by directly pressing Super+number
We cannot detect a running copy of GNOME on this system, so some parts of the interface may be disabled. See our troubleshooting entry for more information.
so I installed it by cloning the repo but nothing happens when I press super+tab. How can I activate it? There is no instruction in the repo's README. – AVarf Jun 30 '19 at 19:48