Send a predefined command by API to only one or selected Displays (not Display Group)

Developer Experience
1

Is it possible to send a predefined command by API, to only one or selected Displays (not Display Group). ?

2

Yes, I assume you mean https://xibo.org.uk/manual/api/#/displayGroup/displayGroupActionCommand

calls like that ie calls that required displayGroupId can be called on displayGroup or single display.

Each display has it’s own displaySpecific displayGroupId, which you can get by calling GET display.