You can define which lights/switches are shared with the Google Assitant. There is a toggle to do that and to select individual devices one-by-one. Unfortunately the same doesn’t apply for Scenes and Routines, they are either all shared or none of them.
I would remove those outside lights from the shared device and I would add some specific Scenes for those lights, like a Scene Outside lights on and another off, then you can control them as you wish, but it will be not triggered by the “turn off all the lights”.
By the way, you can define a “Good night” scene, containing all the lights what you want to turn off or adjust brightness, etc. in SmartThings and you can define the “Good night” routine in the Google Assitant app to trigger your “Good night” scene and any other changes what you want, like reduce volume, start the sound of the ocean etc. Then in the night when you go to sleep, you just need to say Ok Google, Good night