Use your Eero routers as occupancy sensors. There's inherent delay for your devices to swap routers, but for general monitoring this works pretty well.
I use this to automatically open my blinds when we leave the bedroom and go to our main space in the morning.
To get a user token, run npm run auth and follow the prompts:
❯ npm run auth
> @apexskier/homebridge-eero-presence@1.0.1 auth
> node auth.js
login identifier (email or phone, amazon login not supported): hi@example.com
verification code: 123123
user token: 99999999|exampleexampleexampleexamp