Following-up from my comments, to benefit the community summarizing the answer. We have also added this point in the Azure doc.
Currently, the remote screen share function doesn't include function to share audio. Our product team is working on it, but we do not have an ETA to share on this yet.
We have added sharing system audio during screen sharing limitation to ACS Calling feature matrix in the Azure doc.
[The doc list presents the set of features which are currently available in the Azure Communication Services Calling SDKs.]
Thanks for your valuable feedback and patience!
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