The 6502 had a rather unusual history in the USSR. For some not clear for me reasons one scientific institute got interested in the Apple II architecture in the beginning of the 80s. They made a computer which used a card instead of a 6502, it was a prototype of the https://en.wikipedia.org/wiki/Agat_(computer) .
This time the SU didn't buy in mass any CPU chips abroad. People there were directed to clone everything which was worth to clone. They cloned the IBM mainframes, DEC PDP-11, Intel 8080 and 8086. But they didn't try to clone the 6502, 680x, 8085, Z80, 8088, 68k (the 6502, 8085 and Z80 were cloned only by 1990). For some unclear reason, they allowed to buy the 6502 abroad instead of doing its clone. It was the only exception known. It was crazy they preferred to buy popular trade goods instead of processors!
The Agat was not the Apple II compatible. People had to convert the Apple II programs to the use with the Agat. Later, in the end of the 80s, they made a card which converted the Agat into an Apple II compatible computer.
Despite the great shortage of computers in the SU the production of the Agat was at very low level. It started in 1983 but only sligtly more than 10,000 units were produced by 1988. More than 100,000 units were produced until 1993 when their production was stopped. They never tried to make a cheap low-end model, so it was impossible for a man to buy an Agat in a shop. The Agat cost 5-8 times more than other home computers which became available since 1986. IMHO Agat producers just followed the trend from the USA that the Apple II is expensive and solid. Maybe the high prices for the Apple II were a part of the Cold War maneuvers.
The Soviet 6502 clone - https://ru.wikipedia.org/wiki/65C02#%D0 ... %92%D0%9C1 - was made on the base of Rockwell CMOS 6502. This clone has an interesting feature it can use voltage up to 18 volts and this allows to use 5.5 MHz with it. They even produced an accelerator card for the Agat using this feature. So it is interesting was it possible to overclock original Rockwell or other manufactures CMOS chips this way?
BTW the 6502 was cloned in Bulgaria where they could produce a lot of the Apple II compatible computers. So Bulgaria exported its 6502 and Apple II clones to the SU. Moreover the Agat required disk drives which were produced in Bulgaria too.

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my blog about processors

As I recall, the original 4000 series of CMOS logic chips could be supplied with relatively high voltages - 12V maybe? It's just a question of how thick the oxide is. Thinner oxides make for faster gates with lower power, but thicker oxides allow for higher voltages. It's easier to make a thicker oxide, because having a thin oxide with holes in it doesn't work too well.

I would think one advantage of the 6502 here is the simplicity: a quarter the complexity of the z80, so easier to manufacture and you get more good chips from each wafer. Another advantage just might be how easy it was to copy the layout - I'll assume it's an unlicensed copy, so it had to be done the hard way.