and it certainly looks like the van was coming from a smaller side-road.
It isn’t about one road being a foot wider than the other, it is about road classifications. If your on a trunk road or major artery then you have priority and there will likely be road markings to indicate that. No road markings and the chances are that you should give way to the right.
This is actually worth knowing for anybody cycling in countries where this rule applies, if you try to apply some kind of fantasy logic and apply “virtual” road marking as you imagine they would be in the UK giving you the right of way, you could well be painfully corrected.
That said, I have seen enough dash cam videos to not get on a bike in Russia for anything, no matter what the rules of the roads are there, no one seems to give a flying **** about them anyway.