Not as familiar with what types of data collection methods for mental health already exist, but an idea: The ‘sisterhood method’ for maternal mortality data collection, where by interviewing individuals about their sisters maternal experiences you can reduce sample sizes, was a breakthrough in terms of collected maternal mortality data given the various issues with data collection. I can imagine, if it doesn’t exist already, creating a new methodology that leverages peer relationships to collect mental health data (rather than formal entities with some sort of triangulation of data if possible) could possible help and be a new source of indirect mental health data from the population. Factors such as the role of stigma and how accurate peer information is would have to be considered of course.
Social media and mobile data is very interesting, but any solution that involves it must take into account the populations who are less likely to have social media/mobile phones. In particular, girls and women have less access to digital platforms and when they do, more often borrow or share phones and hence data related to movement for example may not be accurate.