C#, JS, SQL, and (AB) PLC Ladder Logic.
I really like working in the dotnet ecosystem; it's well maintained and supported. I'm fairly weak in JS and find it a bit frustrating at times. Mostly because it seems that packages are obsolete or abandoned by the time I'm done reading the docs. I know enough SQL to be dangerous.
Everyone seems to like Rust, maybe I should see what all the fuss is about.
To me, it's absolutely crazy that AC units are even still marketed. An air conditioner is just a heat pump that only work in one direction (cooling). All that is needed to allow it to work for both heating and cooling is one extra valve. If you're going to install a heat pump (in the form of an air conditioner) and a furnace anyway, you might as well let the heat pump provide heating as well. That way, your furnace is only required on the coldest nights. For most of the year, the heat pump is sufficient.