Some Videos on YouTube are showing Nintendo Switch with Lakka and several Games running pretty well in my opinion.
And the thing about "just copy to sd and run lakka" if this would as easy as you can tell.. i tried it and i failed. I hope, if i can efford an samsung evo plus micro sdxc, it will help a lot.
I tried a lot of games. Couldn't get any Wii game to run at playable speed except Super Paper Mario. But quite a few GC games run near full speed and if you set the emulated CPU speed in Dolphin to 40% they will have perfect audio even when there are some slowdowns. I tried other values but 40% works the best.
Paper Mario TTYD is very enjoyable, you can run it at 1.5-2x native resolution with minor slowdowns in busy areas (like some areas of Rogueport) and it looks quite good in handheld mode. At 1x native resolution it's pretty much locked at full speed (but looks less sharp)
Other GC games are hit and miss, even with the 40% emulated CPU speed some games will still have heavy slowdown and audio stuttering. Wii games usually have heavy slowdown and audio stuttering no matter what settings you use.
I tried about a dozen Wii games and a dozen GC games. Of the Wii games only 1 ran at playable speed (Super Paper Mario) still with quite a few slowdowns but no audio stuttering with the emulated CPU tweak and out of the GC games maybe 3-4 of them ran at near full speed, a couple still at playable speed and the other half were too slow.
I was using the MMJ fork of Dolphin on Switchroot. People say it performs the best. I didn't notice a huge difference between official and MMJ though.