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An acquaintance on Twitter asked: "Does anyone know the term for country-specific generalized names, like Ivan (Soviet Union), Fritz (Germany) and Charlie (the VC)?"

I don't think he wants a list of them, but the general term for the use of such names, or for this class of names - "country-specific generalized names" is just too much.
Not only too much, but not enough. Just "country-specific generalized names" doesn't get the point across as indicated by the fact that you had to give a couple of examples. The fact that neither you nor your twacquaintance know of a word suggests that even if you had the word you would still have to explain it, possibly in greater detail than you do with "country-specific generalized names".
Jeff, I don't recall ever hearing that there is such a word. (But I am not an expert!) I was thinking of something like moniker. Then I went to thesaurus.com for "name" and got:
agname, agnomen, alias, appellation, autograph, autonym, brand, cognomen, compellation, denomination, designation, epithet, eponym, flag*, handle*, head, heading, label, matronymic, moniker, monogram, namesake, nickname, nom de guerre, nom de plume, nomen, patronymic, pen name, pet name, place name, prenomen, proper name, pseudonym, rubric, sign, signature, sobriquet, stage name, style, surname, tag, term, trade name
Maybe you could coin a term based on one of these. Geonym, maybe. crazy
"country-specific generalized names"

The French call them blason populaire and this term was adopted by folklorists in the States (link). Pejorative demonym might work also (link). Not sure of a term for blasons populaires which are derived from given names such as Tommy for a UK soldier or the ones you give.
is there a term for terms such as Yank, or Canuck etc. that might be a starting point to coin a term with.
PS welcome Jeff
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