Ever wondered how the electric variable shocks work? I tore one down tonight (this morning?) to find out. Pretty simple and not quite what I was expecting. Video to come.
We would need to figure out the oil volume first but the bottom is welded on and there is most likely a spot to fill the shock with nitrogen under it. Almost everyone uses a needle or a type of schraeder valve for that.
I didn't find any valve for direct filling. I'm not sure how they filled it at the factory. Seems like you could drill a hole and solder a valve stem into it though.