So on my 2019 Subaru Impreza HB, I had the driver's side mirror taken off, which took the stock connector with it.
I have plenty of wire to snip the replacement ones connector and connect the wires(praying an aftermarket brand used the same colored wires) or should I wire in a replacement connector to plug and play with the replacement mirror unit?
This is more or less opinion, but to my way of thinking, you are going to be much better off by wiring in a new connector versus hard wiring. If you EVER have the same issue again, you'll thank yourself. If any body work or replacement of the original wiring needs to occur, it will just make life a lot more simple. You'll be kicking yourself if you ever have to do any of the work again.