The german association of the game industry called GAME has given out prices for sales. The prices are for actual sales in germany above 1 million copies, and more than 500K, 200K and 100K. The sales are reliable, as all the big gaming publishers including Sony, MS and Nintendo. Here is the article in german.

So, Red Dead Redemption managed to sell more than 1 million copies in germany. More than 200K sold Farming Simulator 19, Shadow of the Tomb Raider and Super Mario Party. More than 100K sold the games Battlefield V, Tropical Freeze for Switch, Fallout 76, Spyro Reignited Trilogy, Pokemon Let's Go Eevee and Pikachu (each of them alone actually). This sales exclude sales that are more than 20% reduced in price.

Well it is no surprise RDR2 doing well in Germany

I'd say at least 800k on ps4 if not more.

wow thats awesome, rdr2 doing great in europe

Well deserved