To share devices, invite their account/email address to the home:
Share a home and devices in the Google Home app - Google Nest Help
Note that even if the device only appears in the Nest app, you still need to use the Google Home app to manage home members. The email address you invite must be a personal Gmail account, or if the person you’re inviting to the home uses another email provider, they must create a Google account using that email address. Once they receive and accept the invite, the thermostat will show up in their Nest or Google Home apps, as appropriate.
I don't know the relationship you have with your renters, and what level of control/access you're looking to grant, but you should understand that by doing this they will have the same level of control and access as you. The article I linked above explains what that means in detail.
