D:OS Enhanced Edition only supports local split screen co-op when using 2 controllers. Initially it started off supporting keyboard + controller, but there were issues with mixing the UIs in certain circumstances, and that had to be dropped. Those issues may or may not be fixable or avoidable when updating the UI and controller support for D:OS 2.
Not only was this not not considered, this was asked about repeatedly during the Kickstarter. There will be some customization for the companions.
