3d Tactical Turnbased games using gridmaps for total noobs?

Godot Version

Godot 4.3
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Im a beginner in making games but have a lot of experience in programming , im trying to make a tactical turn-based game , im using Gridmap and mesh library for the terain and AStar3d to compute paths etc.

I trying to understand how to highlight the available path for the players/enemy etc. From what i understood its not possible to directly color/swap the tiles .So probably use a second Gridmap for this.

Question is if i need to show 2 or 3 different type of tile should i have a different Gridmap for each one of them. I figured its a bit of bloatware so maybe there is another way. Can i select specific tile to apply a shader on it or something ?

Some examples would be welcome im using C# but Gdscript can be fine .

Thank you,

It might be unnecessary, but if it works, and you dont have any problems then it should be good enough.

Dont worry about performance until it is a problem