I also tried to see all kinds of fields but none was accepted. Interestingly enough, a GET on the state returns the same data independently if a sensor that is editable or not (specifically - there is no ID)
I tried to change the category of the question to “Development” to maybe reach a different population
Looking at the code, the short answer is you can not.
The post rest call will accept state, attributes and force_update as parameters and when you call it, if the entity does not exist, it adds a new entity to the state machine but at no point does it generate a unique id field or create this as an entity belonging to any type of integration.