It probably took more than 4 to 7 months to do the transfer of players across WoT PC servers for the split from Lesta, if you think that's how long it'd take to merge to entirely separate games that have different tanks, different accounts, different pretty much everything and that's before adding in the complexity of Sony + Microsoft... you are sorely mistaken 😅 .
The legal complexities alone (as Derren alludes to) would likely take a year or two, then the dev resources going into building things that are missing from each other to put them on equal footing would take a long time and mean during that no other work can be done. And that's before you start to consider "what game engine/code stuff is this running on?" because the PC game engine/code doesn't run on console and it seems from your comments you'd want the PC version to be the main basis, so now add in on top of all that they would need to move to a new game engine or entirely rework theirs, that's even more work/time on top.
So realistically it would be a process costing $10's of Millions (if not hundreds), taking several years of work with no development put into pretty much anything else for both games and honestly i doubt most people would be happy at the end anyhow.
Having been around the different WG communities a fair while you tend to find that everyone has preferences and often only see the "greener grasses" of the other side as it suits. While at PC i would get DMs and pings telling me about this great thing console did and it's so bad PC doesn't have it etc etc and then friends from console talking about why they hate that same thing 😅. Both games are different, both have things the others community would like and things the other community wouldn't like.