I need to ask, would Valid be another mutation like Solver, with a will of its own (which at least the series makes clear) and what would its abilities be?
I also wanted to know if a Solver Drone could affect them, or if they also become non-interactable, and vice versa.
How does Valid work
So no, unlike Solver, Valid isn't a mutation-
Its a Cure. At least as far as the users can tell. When it is put into motion, it seems to help in the recreation of structures and the Salvation Drones. From what has been recorded, it is capable of healing the mind, the body, and the Core.
It is capable of fixing mental illnesses and repairing seemingly impossible wounds. Now unfortunately, it has its own mind at times, and will attempt to sometimes fix/cure the user without their knowledge. There are times when it will utterly ruin previously held content and preestablished concepts within your mind. Such as basic stuff like sitting down isn't really sitting, or Murder is better than Salvation. When unleashed on a wider scale, left unchecked, that damage can range from the tame to the cataclysmic.
Since it is capable of curing reality, what makes you think it can't cure you?