it is likely a Pigini era Student quality build
Excelsiola is the model, more or less, this one would be a 4 reed treble
and 4 reed bass most likely LMMH. This is a less expensive version
of the same size Excelsior accordion, differentiated as sharing the
same body dimension/forms/design engineering, but built with
common woods, third party parts, less expensive methods,
and export reeds of course
the "tell" points are the Lexan keytops and the greyish grill material
which suggest "after" CEMEX was absorbed by Pigini, and so of
relatively recent vintage
not an expensive model or particularly desirable except as a
good solid workhorse accordion
does the Allegro website listing have no relevant information ?
i suppose during the War it is difficult getting a western accordion
in Belarus, but there is a company in Ukraine who refurbish
many accordions and post them on Reverb and eBAy, so they
may also have listings nearer and available to your area