@ghostman It’s so cool to hear you’re developing something with Kompakt in mind! 
Our icons are built a bit asymmetrically because of the way our launcher’s grid layout is made and a few other technicalities.
They are originally (mdpi): 81 px x 81 px, with a 40 px x 40 px symbol inside, using a stroke weight of 2.5 px. The stroke of the main, square border is set to “inside” and has a 19 px corner radius.
Hope that helps and can’t wait to see what you’re up to!
PS. Fun fact — by the end of the year, we’re planning to publish the full documentation of our Mudita design system for E-Ink screens.