They seem to play pretty smoothly and full speed on the Pimoroni handheld, although the screen is tiny (under 1.5") and the sound its really bad by default, there is a fix for that but involves some opening up and soldering.
Not sure about the Aliexpress PCBs as never had one myself, the one in this video seems to work ok which appears is likely the one they have all ripped off, but maybe the AlieExpress ones are hit and miss.
As mentioned in the video some games wont work if they are too big but they give a loader error instead of being jerky and the Pico is overclocked to get it running at full speed, maybe the Ali ones are using fake Picos that dont like being overclocked, if thats even a thing.
Github for the emulator here -
https://github.com/fhoedemakers/pico-infonesPlus
