I did this, and yeah google maps is all but unusable without color, that and the camera takes some getting used to.

I'm on an iPhone, but what ended up doing was creating a shortcut that toggles the phone to grayscale and back, and then having two automations, one for when I open any of the apps I actually want color in (maps, camera, photos, etc) that toggles grayscale off and then another automation to toggle grayscale back on when I close any of those same apps.

The option is located in Settings > Accessibility >Display & Text Size > Color Filters

It isn't perfect, but it works most of the time (I also added the shortcut to the back of the home screen so if it is off or I need one-off color I can just toggle it manually).