I've been working on a website that tells you when it's time to open or close the windows. You register with a location, your preferred method of notification, and the rules for what you consider open-windows weather to be.

Range of temperature is the big one for rules, but you can also require humidity, wind speed. Eventually would be nice to add air quality if there's a sensor nearby.

You don't need any local devices - sensors, motors, etc. You just get an email/text/web push of your choice when the weather is nice and some fresh air is freely available.

I've had a home assistant routine for this running for myself for years, but the 80% version requires nothing more than weather data. Human in the loop automation (I physically open/close the windows).