Question about Xiaomi SmartMi 2S

Yes. Install Xiaomi skill on Alexa. Then connect the Smart Mi 2S to the WLAN. Alexa recognises the Venti by itself and tells you which voice commands do what.

In English, it is enough to say: "Alexa, turn fan on" or "Alexa, set fan level to maximum" or "... set fan level to 50%" ("... set level to 1/2/3/4" does not work, power level must be communicated as a percentage, i.e. 1, 2, 3 or 4 would be understood as power level of 1%, 2%, 3% and 4%). It would also work in German, but I mostly speak English with Alexa.

Oscillation can only be activated via the app or on the Venti itself (which is safe in itself because it prevents the oscillation from knocking a pen holder or a small plant off a table or shelf, for example, if it is activated without visual contact and the Venti is near a table or shelf).

I can't say because I don't have Alexa.