A friend of mine does all his veg planting in beds on concrete.
He buys 3″x9″ timbers 16ft long and then makes rectangles 16ft x 5ft and 18″ deep.
He is 74 years old so does some of his digging with a mini digger, which is a good point of having the concrete to clatter around on.
He has great results but he does buy in lots of compost and is on hand for watering most of the time. He just does the traditional spring to autumn season so they sit idle over the winter so I can’t tell you if it works in the cold and wet.
We are in Pembrokeshire with a lot of rain.
There are worms in his beds, which presumably have arrived from the compost he has made and then have multiplied, but I wouldn’t say it is a ecologically balanced soil. They are just huge boxes of compost.