Sounds great that energy efficiency is coming to the mobile hydraulics world. I would think this market would be a natural for EV technology. Even though this is "mobile" hydraulics, much of its use is in a relatively small area, small enough that a plug running to the equipment would be reasonable in many instances.
In reality, a lot of mobile hydraulics work in areas where electrical power would be rather inconvenient. BUT adding a start-stop function to the driver as well as a system to only deliver the required power could be a good start. Using variable speed drive and on/off control valves instead of servo valves offers a good improvement in efficiency, and also has the potential for better performance. The best part is that the biggest new development would be in the controls, not in the hardware. Of course, design for minimum loss is the other requirement, but it is not new at all. These are the ways to double hydraulic system efficiency.
Don't underestimate the benefits of fluid power technology, especially the power densities that are possible when it comes to control of heavy equipment like excavators. A lot is also being done to optimize these systems for greater fuel efficiency.