Disable a gameObject without turning it invisible..

I'm working on something that's basically a collection of puzzles.. each one has to be solved separately and when all puzzles have been solved, the stage is complete.. but I would like that when a puzzle is solved, it can no longer be changed or altered (now f.e. you can "unsolve" a puzzle even after the PuzzleManager has counted the puzzle as solved)...

I would like to disable any input on the panel (every puzzle is a panel consisting of different combinations of buttons, textfields,...) but when I use SetActive(false) the panel just disappears and that's not the result I'm after.. I tried using a dummy panel on top of everything with opacity 0 that is enabled when a puzzle has been solved with Raytracetarget set to 1, hoping it would block the mouse from clicking anything but it's dodgy at best (sometimes it works, but most of the time buttons still register mouseclicks,...) I thought this would work because I had a "frame" (like a pictureframe) sprite on top of everything that blocked all mouseclicks untill I unchecked "raytracetarget" on it..

Any way to:
1) de-activate a Gameobject while still keeping visibility?
2) if possible, use the code on all panels without having to program it for every panel (every panel is different) ?

Thanks