I’m sure there’s plenty of beer-like kvass left over from the Soviet days. I tried some at a small train station in Russia about 35 years ago. It was draft, tapped out of a small tank trailer. Only 35 kopeks. The first glass was pretty hard to get down, but the third was OK.
I tried Kvass in Kiev Ukraine. Just awful stuff.
It is a small dream of mine to someday drink real, actual kvass.
Sure, I have the recipe, but they way you described it is my goal. Off the back of a truck or whatever, and made by real kvassians who know the old ways.