Not a problem…
Create a virtual switch that responds to your motion sensor and select the virtual switch in your Google routine.
Example:
I have a motion sensor in my outdoor mailbox that triggers when opened.
I created a virtual switch that is turned on by the “active motion sensor”
This virtual switch will then be used in Google routine - when switched on - run announce…
Wife hates it but that ok…
Be sure to use the new Edge version for creation or it will not be supported in the future: