“I had already been considering buying an AirThings Wave Plus sensor to monitor my home’s CO2 levels, but the high price and limited ‘ownership’ of the data coming from it turned me off.”
The parts cost $60 to $80 and the data goes to your own Prometheus server, not a vendor’s cloud. The same CO2 sensor costs $30 from AliExpress and $60 from a US distributor. Commercial air monitors charge for the box and then rent you back your own readings. Soldering iron beats subscription.