I too didn't read the article because of the pay wall, but I would just like to advocate for the heat pump at least for those in mild climates. I did it DIY-st

I too didn't read the article because of the pay wall, but I would just like to advocate for the heat pump at least for those in mild climates. I did it DIY-style with the Mr. Cool DIY series. Whole thing was around ~5k for a 18k BTU unit. It looks like the article mentions not enough installers, but the DIY series comes with pre-charged lines so there is no need for specialized equipment to "pump down" the lines or pressure test them. Additionally it counts towards the US tax refund you currently get with it. There was some electrical work done and I think that's the gotcha, I did it myself because I've done minor house wiring before. It wasn't too much to run some Romex in on a dedicated breaker and then out to the heat pump. We had nothing in our tiny 900 square foot house in the way of A/C and were using a bunch of portable space heaters. My electricity bill actually went down from previous years.