I'm trying to figure out which visitor ID is being used and while the debugger shows fid, vid, it doesn't show s_vi.
Based on this post (https://marketing.adobe.com/resources/help/en_US/mcvid/mcvid_analytics.html) it would be nice to show in Debugger:
2. aid (s_vi)
6. Visitor ID*
* This would be the actual visitor ID being used instead of fid or vid.
Unless I misunderstand your post, this is not possible to do, because which one is actually used depends on a number of factors evalutated on the collection server.