Is it possible for value to be objective?
Absolutely not. Valuation requires a valuer. It's not even coherent to speak of "objective value."
Agree.
The closest thing to objective value imo would be mass, or some kind of energy transformation ratio.
This reminds me of a thought I had, that there should be some kind of "objective political power" measurement. And that it should be based on how much actual energy a given person may control, regardless of how he chooses to use it and if he chooses to use it at all.