Mini splits rock in the garage. Put a pair in almost 3 years ago. Prior house had a split system and house before that had a package unit. Live in AZ and got spoiled on garage A/C. Of the different solutions, I prefer the mini splits.
Since then I have installed a couple at work. And have been tapped for info for a handful of co-workers who put them in there garages as well.
But, mine are not low temp units. They don't heat very well. I have seen them that can do a good job of heating, just have to get one that is rated for low ambient temps. Not something that I really care about in AZ.
Friend had a salvage yard. They changed out the A/C units for mini splits. Kept the place cold. Loved them. Saved on the power bill. If one dies, they still have another. A whole new unit can be in and running in a couple hours.