Can I use history_stats if I want to measure multiple states?
For example, my air conditioner also has Cool state in addition to Heat, I want to measure both.
how can i do this best?
create multiple history_stats or can I combine this smartly, if so in what way?
The docs say you can use a string or list in the state field, so it should work. I can confirm that it works on my instance. However, in your example you are missing a closing single quote on “heat” in the list for the state values. That may be what’s causing your issue.
Another option would be to combine a template sensor with your history stats sensor.