Sorry but are there any further details on the main mechanic and why the highlighting is important?
This is because there might be other ways to highlight objects like in this post
Or this selection box.
Otherwise, yeah It’s going to be really tough as you would noted you would need to find the 3d intersection line somehow probably through math which is why yeah high graphics are needed.
Edit 2: perhaps you can squish the problem down in to 2d and use this resource to highlight the intersection shape?
Its meant to be a sort of Echolocation mechanic.
Where everything is black and dark and what i was planning is that when a certain button is pressed a sphere with the forcefield material is spawned on the player and expands and the highlighted edges would let the player see where walls and players are and figure out where to go