Thanks. By the way, there's another living accordion museum (in Russia), and that one started a Facebook page a while ago:
Музей русской гармоники А.Мирека
The Alfred Mirek museum of Russian accordions is a department of the Moscow city museum. Lots of photos and videos on their FB page.
They also added posts with short articles on the history of Russian accordion makers on their FB page, including automatic translations from Russian to English.
I also have my eyes on the Pigini Simba, but I already have something similar, an old Paolo Soprani mini CBA from the 1950s/1960s. A single voice instrument with 31 buttons and 12 basses, a C-system CBA. Net weight is 2,5 kilograms.
27cm high
This Ukrainian (or Russian) mini CBA looks a bit smaller, around 23 cm high. (I have a single voice Russian mini CBA b-system with 22 buttons and 12 basses, net weight 2,2 kilograms, roughly the same size as this one in the Ukraine museum).
Kreminne is a good guess, it's possible.