So really not a lot of people, mostly Russians and countries that have strong ties to Russia.

That's what the first source says and as someone already pointed to a more recent polling showing that it's no longer the case for eastern European countries.

Hungary source is an old article and the same recent polling shows otherwise.

Romania source link doesn't even work.

Eastern Germany is a pretty complex and nuanced topic, one that I won't get into so I'll give that one the benefit of the doubt that they actually want soviet socialism back.

Czech source link also doesn't work.

Serbia source literally has the article saying "the Serbian citizens primarily refer to better economic situation and standard of living, but the majority of them would not go back to that period."

And then there's the Russian part, which is completely understandable considering the USSR was just a form of Russian imperialism.