Yes, there is a function selection that will allow you to activate Siri on your mac using a button on your Quick Keys.
To start, you must open the Settings panel and decide which button on your Quick Keys you want to use to activate Siri.
Note: The Siri activation feature can be added to any Quick Keys, Tablet, or Pens button.
With the Setting panel open.
 Select My Quick Keys.
 I have chosen to have this feature assigned to "all others."
 And I'm going to have it assigned to button #4.
 Select Application from the Menu >  Siri
And click OK to save it.
 Siri is now added to Button 6 on your Quick Keys.
Siri is now displayed on the Quick Keys OLED Display for easy selection and activation.