I created a flow on Homey with
IF this flow is started
THEN put screen to MY
I saved that flow and made it a favorite in Homey.
Then I created a flow in Google Home with
Hey Google, screen stop.
That links to the favorite flow on the Homey where it links to the MY flow.
Maybe this will help you in the right direction.
Don’t know if there is only a MY card or also a Stop card.