Hi,
Sequencer commands don't have direct references to scene objects or assets (e.g., ScriptableObject assets). If you absolutely must have a direct reference, use the dialogue entry's OnExecute() UnityEvent. But only do this if you're going to be working entirely in Unity. External editors such as articy:draft and Arcweave can't directly reference Unity objects of course.
The way to do it with sequencer commands is by name reference or by special keyword. If the door GameObject (see
Character GameObject Assignments) is the dialogue entry's speaker, use the keyword 'speaker'. If the door is the listener, use the keyword 'listener'. Otherwise specify the door's GameObject name -- or actor name if the door has a Dialogue Actor component. In your sequencer command, you can use the GetSubject() method to get the GameObject. In fact, for the example you provided, you don't need to write a custom sequencer command. You can use SendMessage(). Say the door is the listener for a player dialogue entry "[open door]". Use this sequencer command: