Hi.
A television brand XXX with built-in Roku needs a Roku remote ? Or two, one for the TV and one for the Roku ?
A television brand ZZZ with external Roku 2720X as pictured needs what remote ? One for the TV and another for the gadget ?

 

One with a built-in Roku will only need the one remote the came with it.

The external streaming device (Roku) should have its remote with the option to control both the TV and the streaming device,