So the handyman said to get one of those monstrosities that are basically in hotel rooms. "PTACs".
It just so happened that when I tried to go directly to the suppliers website they had a search for authorized dealers section...And an authorized dealer is about 15 minutes away.
When I showed up to get the PTAC, the guy asked what I needed it for, and when I told him a 450 sf garage he said, "why would you get this...you should get a mini split" lol.
Coincidentally, it is the exact same unit as the link I posted (Cooper & Hunter) except 12k BTUs.
He claims they sell them to Home Depot as well.
Anyways, said the PTAC would require cutting a massive hole in the garage vs. the mini split only requiring a 3 inch hole. And it would be more energy efficient.
And to top it off. To run the monstrosity/hotel unit/PTAC required getting an electrician to run a 230 Volt line from house to garage, dig trench, etc...which just to get a dedicated plug was going to cost $1700.
So I went with the affordable / off brand mini split...But it does have decent reviews and comes with 5 year / 7 year warranty (parts / compressor).
They had the exact unit with 115V plug and 230V plug and he claims/says it would not matter and the 115V would work just fine....Hopefully it works out.