Ubuntu MATE 21.04: Keyboard shortcut to show notifications list

I'm trying to find keyboard shortcuts to:

(1) Show notifications list

(2) Clear notifications list

I have gone through this AskUbuntu thread:

https://askubuntu.com/questions/1325785/create-a-custom-keyboard-key-for-opening-the-latest-notification

and Ubuntu desktop guide:

https://help.ubuntu.com/stable/ubuntu-help/shell-notifications.html.en

but none of 'em working for Ubuntu MATE 21.04... because when I open the Menu > Keyboard Shortcuts, there are no entries for anything related to notifications. Also, Super+V or Super+N does nothing.

I can't find any option to view or create keyboard shortcuts in Ayatana indicators settings either.

So, how do I create custom keyboard shortcuts to show and clear notifications list? Thanks.

OS: Ubuntu MATE 21.04

Indicator applet complete: 1.24.0

Ayatana indicators settings: 21.1.28-1

Ayatana indicator notifications: 0.8.90-1