Do you have an old GameCube console sitting around that you're not using anymore? If that is the case, and you also own a Nintendo Switch, you can literally hack (and saw) your old GameCube and give it a second life as a dock for your Switch, complete with working ports. That's exactly what someone did, and it looks awesome.
Image Source: Reddit via Littlewolf128
Sure, it's bulky for a dock. But the fact that the front ports work is what ascends this mod from 'neat' to 'wow, that's really cool!' territory. It's also a well-timed modification, with Nintendo having recently launched Super Smash Bros. Ultimate for the Switch.
The alternative is to buy a knockoff GameCube controller adapter and call it a day. Nintendo released an official one alongside Super Smash Bros. Ultimate, but we couldn't find one in stock. Third-party knockoffs go for around $20 on Amazon.
Reddit user Littlewolf128 went the modded route with a Spice Orange GameCube, a color option that was exclusive to Japan. That in and of itself is nifty. This is not a mod for the faint of heart, though.
Littlewolf128 created the dock by following the instructions in a YouTube tutorial by Rated E Mods. Incidentally, you still need a GameCube controller adapter for this mod, but rather than plug it into the Switch, it gets integrated into the GameCube.
You also have to be comfortable using a Dremel rotary tool to carve the GameCube like a Thanksgiving turkey, and you'll need to gut the Switch dock without breaking any of the parts so that you can assemble the new one. There is some 3D printing involved, too.
It's a delicate process from start to finish, and also worth it if you're handy (or brave) enough to pull it off. In this case, it took Littlewolf128 around "4 weeks on and off" to complete the mod.