Update. My Aqara account was connected to China server (from time of FP2 experimentation). Once switched to US server, I was able to find U100.
Now connected to M3 hub and I can control lock as Matter device thought M3 hub. However, hub needs to be close to Lock. I am planning another lock, so need to extend Aqara zigbee mesh. Not ideal (to say the least), becuase I already have 2 zigbee network at home. That will be third