Usage Metrics (Report Server)

Hi all.  I'm trying to build a usage metrics report using the Report Server execution logs.  I was hoping to get some consumption details like the service usage report has.  This would be determining if viewers are on mobile app or website; and possibly which browser they viewed from.  This would be helpful for determining which reports should have/need a mobile optimized view; as well as diagnosing issues reported by specific users saying reports take "forever" to load.  I haven't found anything in the tables I've been looking through (incl. ExecutionLogStorage and the 3 views associated).  But if anyone knows where to find this information, I'd be appreciative.  Or just let me know its not possible and I can stop trying to look for it.  Thanks.