Pumped hydro is a form of gravity battery. It doesn't have great energy density, but it has fantastic power density and responsiveness. That's where its strength lies. We have also probably already built most of the ones that could possibly be built.

Closed loop pumped hydro can be built anywhere there's a hill, there's tons of available expansion capacity there

There are 86 large pumped storage sites in the world. It does work, but you need the right geography. You need two good reservoir sites at considerably different levels close to one another. That's somewhat hard to find.