Also, make sure that's actually legal in your jurisdiction. It is not legal here (primarily due to handling of coolant)

Good point, though you generally don’t really have to handle coolant for mini splits, they come precharged. You mainly have to add more if you have a longer lineset.

I’ve heard the online EPA course/test for coolant cert is pretty easy, though.

The main thing is just making sure you test the lineset well, including deep vacuum decay, and ideally a nitrogen high pressure test.

Even where it's not legal you can often do much of the work and hire a licensed contractor for the "final step". It can be worth asking around.