I am going to assume that your Roku OS version (9.1) is the culprit.
I do not see any Roku documention specifying minimum OS number to view the cameras on the Roku Camera channel/app, but normally the channel/app will only be seen on/available on supported devices and OS builds.
Edited to add - looks like OS 11.0 is required to add channel and view cameras. https://support.roku.com/article/7873923625751 (How to view a live video stream from your Roku Smart Home camera or video doorbell)
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