There was also the "build it to live in it" condominium programs that opened more opportunities specifically to those just starting their adult lives, who would otherwise qualify at most for a room in a communal apartment, and couldn't possibly afford a downpayment on that mortgage (15-20 monthly salaries). But those came late - many weren't even completed by 1991 - and they had considerable pushback from many local authorities, partly on the basis that such luxury was "undeserved" and unfair to older people who were in the line for regular apartments, and partly because some of their member-elected governance councils were starting to get political ambitions and push for more local self-administration in the 80s.

That was similar in a lot of post-war Europe, e.g. for my grandparents in the UK.

The Americans have always lived in abundance and luxury in comparison.

The allotment of living space (counted as bedroom area per person) varied depending on the city, and sometimes there was a difference between the nominal and the actual number. In Moscow and Leningrad the designated minimum was around 7 m^2 per person, but in practice applying for a new apartment would be unlikely to succeed if you had more than 5 m^2. In some of the provinces, it could go as low as 3 m^2 per person.

And keep in mind that this is the minimum that entitled you to apply for a new apartment. Which means that you'd be put in a line to wait your turn to actually get one when one is available, say, 10 years later.