Supposedly Google imposed privacy policies in Android 11 that hindered Smartview from casting to anything other than other Samsung.
For Chrome cast, they suggest using Google Home. Fine, but what about Firestick?
Something doesn't sound right here. You'd think if it was due to Google's implementation of Android 11, you would have heard about this for other brand Android devices.
I just tested Smartview on my S20 FE with Amazon Firestick. It worked, the fitestick showed up in the SmartView device list once I engaged mirroring on the Firestick. Not sure what protocol Firestick uses, seems to be Miracast.
So the issue might only be with Chromecast.