These people don't want to save the world. They just want to look like heroes

I agree. But it doesn't mean these people can't do good things and this system seems a good thing to me. Is it perfect? No, as you said

this kind of system seems limited to small cash crops rather than staple foods.

So that's a problem. But it's a step in the right direction.

Dyson has personally done far more to harm British food security than this gadget could offset. He was an ardent Brexiteer, which resulted in substantial barriers to importing food from our closest neighbors.

He is absolutely and unequivocally a wanker. But if he's done something good here, it will mean alternatives will become available and that's a win for everyone.