Remotes fully interchangeable?

Roku has its "simple remote", which controls via infrared (IR) signals.   All roku devices with IR receivers respond to the same set of IR commands so for those Rokus the simple remotes are interchangeable.  Universal IR remotes that have built in commands for Roku devices are interchangeable for IR equipped devices as well.

Roku tvs come with IR remotes, but they use a different set of IR commands than Roku devices do.   IR remotes are not interchangeable between Roku devices and Roku tvs.

Roku also has Voice Remotes that control by wifi.  Roku Streaming Stick products can only be controlled by wifi, as they are normally used behind the tv where IR cannot reach, so they don't have IR receptors.   Roku TVs and all but some fairly old Roku devices are compatible with these as well.