Google Home has only ever allowed for a rudimentary all-or-nothing approach when it comes to managing household members. You can either grant someone full access to your smart home devices or none at all. Based on recent UI tweaks, Google is looking to change that and might introduce tiers of different access levels soon.
When you go to the Google Home settings -> Household, you'll get to a list of all people in your home along with the usual option to invite another person. What's new is what you see when you tap an individual in the list, including yourself. The new page shows you which access level someone has and which devices they can control: Access details and Devices. Right now, it's still an all-or-nothing approach. Tapping the Access details entry only shows you a new page with an explanation that "everyone in this home can view all activity and access all devices and settings," so everyone has the role of a Manager. The same goes for the Devices menu, though it additionally lists every single smart home device in your house.
Implementing these tweaks just for the sake of change wouldn't make a lot of sense, and the way the interface is structured, it's just intuitive to assume that more granular options are coming. And sure enough, 9to5Google already spotted some strings back in September that point to just that. The code suggests that you'll have the option to grant people access to smart home devices based on a schedule: "This person will have access to the selected devices during the following schedule. Carefully review and edit before inviting." That would be similar to the user roles and access levels the Nest app offers, which will be great for restricting kids or roommates from controlling devices in your room, office, or bedroom.
Right now, we're only able to see that everyone has full access to everything in the Home app, so we'll need to be patient until Google releases the new detailed options to the public. Let's just hope we won't have to wait until Google I/O 2021 for that to happen.
You can download the most recent version of the Google Home app from the Play Store or over at APK Mirror.