I don't understand why some people are trying to make it difficult for you. CDPRed has made witcher, witcher 2, witcher 3, The Witcher Adventure Game, Thronebreaker: The Witcher Tales, GWENT: The Witcher Card Game and they are making Cyberpunk 2077. GOG and CDPRed are parts of the same company. If you want to support them just buy their games for the full price. The whole will support the same company.
I'm not 100% sure but if you want to support GOG for the most part, you should try GWENT and buy in-game items because as far as I know GOG is financially responsible for this product.