Well the research is being handed to me on a platter, 2/3 of the techs to get a fleet carrier were just stolen, at random, from the allies. I just feel like the soviets would have acted upon that, ie at least build 1 CVL, and maybe a CV (the 'Iosif Stalin', anyone?) The carrier would be of use against the Kriegsmarine, and/or the Italians, because it would be possible to keep non-carrier enemy fleets at bay while the CAGs hammer them till they sink (considering I have pretty fast escorts, for example CV+DDx6 should work). A further use could be as a mobile Air base for air support in the Black sea, and the Baltics especially. It would still be a side show of course. We'll see...
In my view one big advantage of the Carrier in this case is that much of the punch of my CV/CVL will depend on the CAG's Air techs/doctrines I would have researched anyway for CAS and Int fighting the Luftwaffe.
Considering the pace of Industrial expansion I think we can afford one CVL at least, the committee is planning to start construction on one once the last DD is built.
In the long term we might swarm the USN/IJN/RN with mass-produced large sort-of primitive carrier groups with very advanced planes, and just play the numbers game in the sky overhead. If my screens are fast enough it might even work against combined fleets... Fast cruiser fleets would still be a problem in the late game however...No naval strategy is perfect...