GSA is hardly obscure. Every federal bureaucrat knows who they are ~ they provide the buildings, turn on the heat, run the AC, guard the buildings from marauders, paint and repaint the parking lots in an endless cycle that succeeds in filling every crack over a 20 year period, etc.
The GSA is in charge of getting the FBI a new building. Seems their old building (which many of us watched built since it was a 15 story deep hole in downtown DC) is crumbling into concrete dust ~ GSA managed that contract too.
The GSA does the federal court houses.
The rest of the capitalist world seems to provide themselves buildings and keep the power and AC on just fine without an entire federal bureaucracy of overpaid bureaucrats offered lifetime pensions.
That’s what I actually meant in my Post #5: I don’t know exactly what they do, as they try to do so much, so very badly. (I just didn’t express it very well.)