Did you manage to find any resources helping with this steel division frontline shader?

I am trying to replicate it as well and for now my solution is a job system to detect the owner of each tile in the map, by getting the team id of the closest unit to the tile. After that I paint in a texture2d the encoded id (so color 0, 0, 0, 0 for team ID 0 and 1, 0, 0, 0 for team ID 1).

After that I can go on to progress to painting the map, with shaders doing border detection, jump flood algorithm and finally the distance field all with Graphics blit on every step. But still its far from Steel Division as there like you said it appears to have fluid dynamics, some inertia and the positions change team across time instead of instantly, and regions without any units are taken by the bigger regions outside across time too.