Casting browser tab to AnrdoidTV/GoogleTV (Windows desktop)?

I use AndroidTV quite a lot, mainly for ad-free youtube on the TV and the stellar... 3rd party streaming apps. I recently found out that Chrome allows you to cast a tab on PC to AndroidTV; not media playing in a tab, but the entire tab itself, allowing you to use it as a mini version of a second screen for an individual tab at least.

I don't see this feature available in Brave. The Cast button (the music note icon) disappears entirely if there is no cast-able media playing in a Brave tab, and there's nothing in the settings menu to bring it up like there is in Chrome.

Am I missing something or is this just no implemented in Brave? Brave supports Google Cast in the traditional manner, so it seems this would be an easy feature to implement.