One aspect of a study in Insights Platform are the Device Type statistics. These provide a nice overview of the types of devices used by the end users at the point of interacting with the studied subject.
Device Type statistics on the Overview section of the Study Explore page
Device types are detected using the User-Agent header which HTTP clients voluntarily provide to the server. From the header we can usually detect the type of device, operating system and browser of the client.
This approach is very common and generally works well. Note however, that a common misconception in the advertising space is that ad format and device type is not always the same. For example, you can have a campaign that targets CTV or AVOD TV channels, and it is quite common not to be serving those ads on actual TVs! An AVOD TV provider is often times also serving ads through video apps or in-browser experiences on desktop and mobile devices.