I'd agree, an underplate for 'something' is more likely than a 'plate' in the ordinary sense, due to the size. You might have more luck concentrating the search using 'copper wheel engraving', but unlikely you'll have luck in getting an id in the way of maker or country of origin, although on balance and if pushed you might be better off thinking British.
Silber & Fleming (c. 1880) include underplates/plates of about the same diameter for ……….. apparently biscuit boxes/barrels had them on occasions - butter dishes likewise plus, when they were sold on their own, - ice plates it seems.
The absence of any 'ferny' look to the engraving might suggest early C20 rather than Victorian though doubtless not a hard and fast rule, and the actual appearance of engraving is probably fairly commonplace, with the circles of repeat dots, ovals and lines (also seen on the Steuben example), so nothing unusual to guide a search. Wear, or otherwise, might give a hint of age, but frequently unpredictable/unreliable - date wise could be anywhere from mid C19 to 1920s. How many do you have?