CD Projekt Red, the company that is making Cyberpunk 2077, also owns Good Old Games (GoG).

If you purchase Cyberpunk 2077 from GoG, not only does CDPR get 100% of your money, but they also include a DRM free copy of the game. You can take it anywhere, install it on any PC.

Steam uses their own version of Digital Rights Management (DRM.) Basically it just means you need to have the steam client open when launching and playing a game. Even if you're playing offline or without any Internet.

Since Cyberpunk will be a single player game first, it won't require internet to play the campaign or launch. But if you want to play without a client open, you'll need the GoG version.