Thank you. Now I understand your earlier comments as to what I was asking did not make sense.
If I want to see a list for the blocks having 1 particular topic value I have to do a simple query {{query (property topic value)}}.
I am still in the process of wrapping my head around properties. I just read mentaloid’s Generate explicit hierarchy out of properties - very impressive.
My workflow is too simple at this stage to use his model, but I have bookmarked it.