Scalable Mesh

So hello,

im trying to build an App which supports me GameMastering Pathfinder and D&D.
So the basic Setup is a plane which is projected to the table. On that plane i aplly a picture as a decal (which is by now the only solution working for me), im also trying to convert the picture to a sprite which works in some cases pretty good.

But what i need is a mesh on top of the map.
This mesh should
-scale with the zoom
-every cell should be an actor
-for this problem i got 2 solutions it could either the cell itself (dependent on if its an actor or not), or just an collider at the specific coordinates, which i believe is pretty fast and compatible

I have tried several things like spawning multiple meshes, spawning meshes as instances of each other, which greatly improved the performance but its still not usable. Spawning particle emitter to make visual grid…
None of them seem to be a good solution.

I attached two pictures from Inkarante an Map Making App i´m using. There u can see what i´m trying to achieve.

Any suggestions?