interactionPrompt property
Allows you to change the conditions under which the visual and audible interaction prompt will display. If set to "auto", the interaction prompt will be displayed as soon as the interaction-prompt-threshold (see below) time has elapsed (after the model is revealed). If set to "when-focused", the interaction prompt will only be activated if the element has first received focus. The interaction prompt will only display if camera-controls are enabled.
You man use the InteractionPrompt enum to set this attribute.
<model-viewer> official document: https://modelviewer.dev/docs/#entrydocs-stagingandcameras-attributes-interactionPrompt
Implementation
final InteractionPrompt? interactionPrompt;