Personal computing devices are often not literally ‘personal’ in practice. Device sharing, i.e. two or more persons using a device, is a common phenomenon in everyday life. With multiple different layers of software and accounts, the interactions between them in a device sharing scenario become complex, leading to data protection and other risks. With the goal of gaining insight into how the industry considers this topic, in this mixed-methods study, we examine the approaches software providers take on device sharing in their policies with systematic content analysis. Furthermore, we examine the indications whether these approaches are present in the current capabilities of the devices as platforms, with systematic black-box testing. The results reveal a complex and partly ambiguous landscape of different approaches, highlighting potential areas with a lack of alignment. We identified 18 common approaches in policies to manage different aspects of device sharing and clarified the ‘border’ between operating systems and applications.