Transferable regional game keys? (sourcing)

[[MPGH]arunforce]

Most games are set up for regional distribution, e.g. asia, europe, usa. You find the country with the lowest purchasing power and you buy through there (e.g. phillipenes) where they price games locally to encourage purchasing in real means rather than a global price.

[KulkuriS]

Most games are set up for regional distribution, e.g. asia, europe, usa. You find the country with the lowest purchasing power and you buy through there (e.g. phillipenes) where they price games locally to encourage purchasing in real means rather than a global price.

Yes I totally get the regional pricing, my question is how do you source resellalable keys?

I am able to find keys for my personnal use with regional pricing, but those keys cannot be shared.
That's why I wonder how those sellers on marketplaces (G2A, Kinguin, etc.) do:
do they have an "official" game store in these regional countries to get "sellable" keys?
Or is there another way (exploit bug with gifting method?)