It depends on your definition of useful. I can control the basic elements and some of their offshoots. Some are stronger than others. The one I can't fully control is ice. My specialty is plant manipulation. At least if they cut us off from the kitchen, I can force plants to grow for food, even if they limit it again with the PIP.

[He might not care, but all of this sounds very forced. She doesn't want anyone to know even if right now they kind of... have to know.]

I can generate electricity. It's not very fine tuned, but I can power items for a small amount of time depending on what it is, or use it in an offensive and defensive fashion. Nishitani can attest to that.