I have created the following Shortcuts that can be activated with <kbd>F9</kbd> and <kbd>F7</kbd> (Tested in macOS Ventura 13):

 - [Forward By 10 seconds][1]
 - [Backward By 10 seconds][2]


Just double check that "Pin in Menu Bar" is checked and "Run with" have the desired keyboard shortcut. This way they will work even if the Shortcuts app is not active:

[![Screenshot of the settings to double check][3]][3]

I just noticed some apps already have <kbd>F7</kbd> and <kbd>F9</kbd> shortcuts that will override the action for these shortcuts. So you probably can change them to <kbd>⌘</kbd>+<kbd>F7</kbd> and <kbd>⌘</kbd>+<kbd>F9</kbd> or whatever shortcut that doesn't conflict with the active app you use regularly with picture-in-picture.


  [1]: https://www.icloud.com/shortcuts/ebd6b399c5154367b49124d313aef1ba
  [2]: https://www.icloud.com/shortcuts/02cf0870552c43dda69d4a7105c62be8
  [3]: https://i.sstatic.net/SmMyV.png "Screenshot of the settings to double check"