I am new to Home Assistant and am making good progress. I have 2 65" Vizio TVs that were discoverable with the SmartCast Integration. I only really wanted to have the ability to power on and off. The SmartCast integration doesn’t appear to do that. I could only get the Media Player on/off to work and that only started and stopped ChromeCast.
After some Reddit searches, some folks suggested integrating with HomeKit. I added the HomeKit integration and followed the instructions to find the HomeKit pairing code and was able to add both TVs and can now power the TVs on/off.
Just go to the Extras menu in the SmartCast software and click through to get to the HomeKit/Airplay setup.