You need Node Red a Alexa Connector and an MQTTServer.
You connect Alexa to Node Red and pass on the States of what ever you want to do via MQTT this is how i did it in 3.16 and Later.
Depending on the Alexa Plugin in Node Red you can even ask for the State of Scada IOs for example Temperature Pressure etc.
There is no official supported Driver for OA though. So You need to do it yourself.