There are two parts to answering this: when did the word widget come into usage in this context, and what about its meaning as an abstract unit of production?

Widget has been in use since at least 1931, perhaps earlier. It was definitely used in a few earlier sources, but not necessarily with the same meaning (and sometimes with alternate spellings such as widgit). One records of its usage with the current meaning was in the late 1930s by the some of the powerhouse motor companies of the time. There's no definite answers as to its etymology but OED and a few other sources suggest it's a corruption of gadget. In this sense, yes, there have been other 'fake commodities'. Gadget goes back to the mid-Nineteenth Century in naval parlance for a piece of machinery whose name can't be remembered at the time (see its use in the works of Vivian Drake). There are some folk etymologies to do with a company owner named Gaget but to my knowledge there's no serious evidence for these. More likely (pure opinion here, though OED seems to agree) is that it's related to gâchette, French for a mechanism piece. Widget apparently entered American English in economics during the 1920s but I've found nothing substantial that attests to this.

So, the general population certainly seemed to use gadget as a placeholder for 'thing' before using modern derivatives such as widget and gizmo. Economists took a slightly different approach. Prior to the Nineteenth Century, economists tended to use either specific hypothetical cases "John produces 200 wheels", etc. or stuck to jargon such as Adam Smith's "commercial product". Common necessities were frequently used such as "bushels of X" (see the work of Marx or even Hobbes for examples from political philosophy).