Does ANYONE know the actual Size (metric or standard) of the 938-22 "DISASSEMBLY TOOL" used with the standard 938-22 3.3" barrel (which is really a micro sized short Allen Wrench)?

I suggest that you ask that question on the Sig Talk forum. There is sub forum specifically for P238'and P938's :- https://www.sigtalk.com/forums/p238-p938-pistol.52/

Glad to see you got a positive response on Sig Talk. They are a great bunch of helpful folks.