As a general rule, pre-war Hi-Powers had tangent sights & stock slot. Post war Hi-Powers were primarily fixed sights. As I mentioned this is the general rule.
Looking at the picture you posted and the serial number given, at first blush, I would be inclined to think that it is a post-war Hi-Power because of the fixed sights. The finish you indicated could be either pre-war or post war.
The pre-war Hi-Powers started at serial no. 1. But, when FN re-started production after the was, they also started at serial no. 1. (This does not include the contracts, of which many started at serial no. 1.) Consequently, it is possible to have two Hi-Powers with the same serial number, one is pre-war and the other is post-war.
But any general rule has its exceptions. There were fixed sight Hi-Powers manufactured before 1940. Not very many I would assume since production was geared to the Belgian military and the various foreign contracts. Argentina and Peru did receive contracts of Hi-Powers with fixed sights (which had special markings). Also, there were a few made for the commercial market. I have one that is numbered as serial no. 11202 (fixed sights but with a stock slot). There are a few other known examples, most in the 10/11 k serial number range. For referencfe. the serial numbers of the known commercial Hi-Powers have been recorded in Anthony's book.
So it is possible that the one you posted was pre-war.