Ditto. Would love to figure out if there's a good way of mapping out layer 1/2 connectivity from a single computer as well. Would be really, really fascinating.
There are other ways of acquiring layer 1 data which are labor intensive and involve the equivalent of filing FOIAs for construction permits with local city and county agencies, etc.
Big facilities based ISPs that have a lot of fiber out there underground and aerial make extensive use of GIS software. Their construction groups will have their own full time GIS staff positions.