Website and subdomains: duplicates and geo-dependent requests?

Question

Search Engine Optimization

Dear optimizers, tell me how to solve the puzzle. A large company has an IM site of the type
site.ru and branches (more than 30) with sites of the nsk.site.ru format.
The texts of product catalogs and news are the same on all sites (because there are more than 6,000 products in the catalog, it is difficult to unify texts for 30 branches).
There is a problem of duplicates - Yandex does not like copy-paste and, in theory, it is necessary to close directories in branches, but if we remove subdomains, we will lose geo-dependent queries (like buying an elephant in Samara).
How to be? After all, how do sites like Mvideo and Eldorado solve this problem?

Answer 1

alternatively use rel="canonical"