Is there a way to see a snapshot of open PO amount as of any past date? Taking consideration the closed PO

in NSAW and OAC you might be able to do that, basically you are asking for slowly changing dimension.

But not in NS itself? I thought the standard open PO report would do that but apparently not. I tried recreating it with a saved search but I'm having issues with closed lines as they are driven by a transaction. Could only track them via system notes

Yup, system notes does have that data