If you buy any games on GOG now, you can export them to Steam. 100% of Cyberpunk profits will go to CDPR if the game is purchased on GOG, which is owned by them.
you can import the lancher into steam, like you can with anything. but I could not find anything stating you can get a steam key for a GOG game and import the key into steam. I looked everywhere on my witcher 3 install and there are no keys to be found..