I can play Wind Waker on my Pixel 4a, a mid level phone from a couple years ago. I imagine if apple could be arsed to open their stupid ban on jits you could emulate switch titles without a hitch on iPhones.
You probably still want a game pad for any 3d titles tho, on Gameboy on screen inputs are fine but the lack of precision can be really annoying to get over. Fortunately the xbox controllers work out of the box with dolphin.
I see, the last time I looked into this was shortly after apple closed the last known jailbreak options and before they allowed jits in some circumstances.
The lack of a speed difference I assume is down to the fact that delta supports some pretty weak consoles which you could emulate in a browser. Dolphin's jit vs interpreter vs cached interpreter in for example Wind Waker is a 10-40x speed improvement on my phone.
You probably still want a game pad for any 3d titles tho, on Gameboy on screen inputs are fine but the lack of precision can be really annoying to get over. Fortunately the xbox controllers work out of the box with dolphin.