I came across the Wikimedia Unique Devices data set, which also is served up as an API endpoint, along with the other APIs the platform offers. The data set and API provide access to a list of unique devices that have visited Wikipedia for a specific period of time.
The data set and API only have data back to January currently, but I'm sure this is something that will evolve over time. I really like the fact that we have organizations who are operating at scale, and are open and willing to share their data. This type of information is high value, and is something that can help us all better understand the ever-shifting digital landscape around us—thank you Wikimedia for making accessible.
While playing with their Unique Device API, I also noticed how transparent they are with their page view data, also making it available as a simple set of API endpoints. I know Wikimedia is a non-profit, but I can't help but feel their way of doing things provides a blueprint that other commercial platforms should consider following.