What can each player render?
Use browser/Pi for highest renderer fidelity and the generated Roku widget compatibility reference for the native player boundary.
Browser and Raspberry Pi use the browser renderer. Roku uses a native Relay Plan compiled from the published SceneDoc. Fire/Android are browser-compatible today and should be tested on the exact hardware.
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.