None of these uses MQTT.
All drivers in this thread use either http or http+websocket
ShellyAsAswitch is for Gen1 devices mainly. It might work with Gen2+ devices if they do provide Gen1 http endpoints.
Gen2+ are:
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Shelly Plus is using http polling to get switch info (latency depends on polling interval)
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ShellyPlusPro-xPM is using websocket (nearly instant feedback but at the cost of heavier hub load; shellies are chatty)