have you tried experimenting with kangaroo curve collider + some sort of magnetic attraction?
this is just a silly experiment using the custom PLaw goal from this post Magnetic attraction/repulsion - #2 by DanielPiker
Mosaic_Re.gh (20.7 KB)
you can play with the k slider to increase or decrease the magnetic attraction force, once pieces are close to each other or even compenetrating a bit you can set it to zero in such a way Curve Collider goal strength wins again and tiles relax a bit
if you want to leave some sort of grout line distance between pieces, you can apply an outside offset to each piece of amount “half total grout thickness” to the starting tiles
by the way, not a Kangaroo expert, I just like a lot to play with it 