And that would be the limiting factor. It’s relatively easy to build hydraulic cylinders with seals that can hold the pressure and hoses that are Kevlar braided. But to produce the PSI and GPM that would be required to power it, would be difficult. A large tracked excavator has a 6 foot long engine in it that really is just a big hydraulic pump to power the drive train and boom. The engine required for Hex legs on a real tank would have to be 3 times the size. Which means the legs have to lift a tank, and engine, plus the weight of the steel arms, plus the weight of the pump and engine. The hydraulic system would weight almost as much as the tank.
The only possible way, that I can see is not more power but to lighten the tank. Carbon Tow, Titanium, Aluminum and honeycomb core parts could easily cut the weight by 60 to 70%. However all the component would have to be redesigned to be structurally strong with the new material. Not to mention that the cost of the materials alone would change 1 million dollar of steel into 1 billion dollars of exotic materials. Plus fabrication, design, testing, and labor.
So, who know where to get a government grant? 