This document:
https://docs.google.com/spreadsheets/d/1oL6ldkQdLu-4FEQE0lX6BcgbqzYfNnd1XA8vERe0vpE
Tab "layer resistances and capacitances" has a table "electromigration rules (estimated)" at the bottom.
That tells you how wide any single metal layer needs to be to sustain a given current without violating electromigration rules.
We got no such rules from SkyWater so I calculated estimated values using other PDKs and the metal material (Aluminum) and thickness.
So for metal1, for example, with 0.65mA/um max, for 240uA current you should be okay with a metal width of 0.37um.