If I look at the HA log, the thermostat seems to disconnect and reconnect itself every few minutes. Does yours do that? After looking closer at it, I think this is an issue with the Rheem thermostat not staying connected to the home WiFi network.

Also, have you considered wiring in to the thermostat directly to avoid having to use a Rheem account?

Unfortunately my furnace (Rheem) only works this way which is so disappointing. I wish it could be cracked so that it could work independently with home assistant.