The thing with FPV drones is detection ranges tend to be low, especially through ground clutter. Your trench radar won't see the fpv at ground level beyond the next treeline. So you have very little time to react when it does show up. Also radars are emitters and draw attention. Add in the fact that it cant turn a full 360, and I suspect this system won't work well for this purpose.
I do agree, this system has been developed to protect installations and it's going to be a long while until Russia gets something like enough of them.
You have a system that seems to work, you have a radar that works (within limits), you have to develop it for field operations, making it, at least some of them, SP. Then they will have to target the system first... then they will use artillery against it... then you target their pilots... then you hit their artillery... I know, it's just another tool to make drones even less efficient, to
move or even to make certain (open) areas drone resistant.
It's not a silver bullet, but units have been working under air attack, and taking casualties.