Hi did you get anywhere with your system? I only have a few different wiser devices (powerplug, motion, and temp sensors) all work instantly with zha. Nearly gave up on the powertag untill i removed it and the gateway from wisers app and added them in the tuya smart app instead. Now they both show in the tuya cloud api which is something i guess.
Update
Using this fork of localtuya: Local Tuya - Control Tuya devices locally (Fork from localtuya)
I could add the powertag and get the readings.