What can each player render?
Use browser/Pi for highest renderer fidelity and the generated Roku widget compatibility reference for the native player boundary.
The web player and Raspberry Pi appliance use the browser renderer. The Google TV direct APK hosts that same renderer inside a native TV shell. Roku uses a native Relay Plan compiled from the published SceneDoc. Fire TV currently uses its browser-compatible path.
Roku compatibility rule
Widgets declare their Roku strategy in the widget/relay registry: local, native-data, native-media, snapshot, or unsupported. The /docs/widgets page is generated from that registry. Arbitrary Web Embed/YouTube-style browser content should not be assumed to work on Roku.
Do not re-pair a healthy screen to solve unsupported content. Replace the unsupported element or use a browser/Pi player for that screen, then publish again.