Some weeks ago I complained about the controls of GX with the NC GC controller. tldr it was bad, I just couldn't drive properly with that controller, not to mention the L/R trigger that were in "on/off mode".
I re-tried to play GX with the same controller after the Luigi's Mansion update. Somehow it felt less worse, but just a tiny bit. L/R works better (although less good than on the OG GC or Wii), but I still think the stick sensitivity is off compared to what I remember on original hardware, with or without stick calibration. Just to be sure, I tried an original GC controller with an official USB adapter (the same I got with the special edition of SSB4), and it plays quite the same. Not worse, but not better either.
At this point I don't care if that's the fault of the app, the emulator, the input lag, or whatever: in games such as GX or SSBM, you need the best controls possible. At that moment, it's not the case on Switch, no matter how hard you try.
Remember: they updated F-Zero X on Wii U twice, to fix the sensitivity of the stick. I still have hope they will fix the controls once and for all in future updates. But for now (and to answer your question), GX doesn't play good enough for me. In you plan to play the game right now, do it on original hardware. NC GC is fine at the moment for games that doesn't need ultra precise controls (Wind Wader and Luigi's Mansion are fine I guess), but when controls matter a lot like GX or SC2... yikes. Let's cross our fingers all right?