There are a few good answers here already, so instead I’ll go ahead and ask: Why a GC controller in the first place?
This is just my opinion, but unless you’re going for absolute authenticity over any kind of comfort, I’d just use any modern controller instead. Unlike the Wii Nunchuks, the layout maps to modern controllers pretty well, particularly to Xbox-style controllers. The GC doesn’t have that many exclusives either that would make a purchase worthwhile, since many of them got ports/remasters/remakes over the years.
So my advice would be to start emulating using a regular controller first, and only grab a GC controller after a while, if you still feel the need to get one at that point.