Hi Ben, now that new-mm becomes usable we have an internal project (code name trailblazer 😀) where we port one vertical slice, i.e. one feature of an already existing, real world, customer app from network stack to ViewModel to kmm and integrate it with the existing Android and iOS app and their existing UIs. I'll write a blog post about that soon.
Spoiler: works even better then expected but date time and general obj-c interop can be painful.