The currently announced new member of the Raspberry Pi family - the Raspberry Pi Zero provides only digital audio out via its HDMI connector. What are the options to add analog audio out to this model?
Answers should address both hardware issues and respective software aspects considering the integration in state-of-the-art software frameworks of the Linux kernel, such as ALSA. (E.g. PWM-based audio like with other Raspberry Pi models seem fairly simple in hardware terms and could be plugged to any GPIO pin; but how would this solution be seamlessly integrated into the systems device drivers and the API?)