What's the solution for heating and cooling a renovated attic space in a cold climate?

I recently bought an older home where the main bedroom is located in a converted attic space. It's cold when the heat is on and hot as all hell when the ac is running.

I've had multiple people come out with varying suggestions. The first two suggested a mini split system. Then another person came out and told me they suck for Minnesota weather as they cannot provide heat under 14 degrees, which it is enough of the time.

Then the person who told me that was a bad idea suggested a second furnace/a.c.unit just for the top. That sounded great until....

Fourth person came out and told me the upstairs was too small (~500 sq ft) that even the smallest furnace setup would cycle on and off so much that it would die quickly, and that where they would have to put it (crawl space) has unconditioned air, so the efficiency would be low, around 80%. They then gave me a 14k quote to rework the duct work with no promises that it would fix anything.

The rest of my house is fine, it's only the upstairs that I want to fix. It gets over 90 degrees on a hot day, even with ac running. I added insulation and that helped, but it really needs some kind of hvac system. Would any second system be appropriate up there?

Thanks for any suggestions.

submitted by /u/elohel888
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