Yes, I have done all the steps you indicated, but I am still at the same point. If I scan devices from Alexa, I get this log:
[WARN] [io.openhabcloud.internal.CloudClient] - Jetty request 9760960 failed: null
[WARN] [io.openhabcloud.internal.CloudClient] - Response Failure: null
Is this something related to openHAB Cloud service?
I also tried with Google Home and I entered an item
Switch Tuya_Door "Tuya Door Sensor Test [% s]" <door> {ga = "Switch"}
but even in this case I don’t see the item exposed (in this case on Google Home).