I know that for the GOG version of this game (maybe even steam one, I think?) you can't choose your name, as the game just used the account one in the past. Is it still the case? And if so, what happens if you play the non galaxy version?

Thanks for anyone answering to my questions. :)

When I tried to change my user name I had to submit a request to GOG and then go through several emails in order to finally find one that was not already in use. This was before I even downloaded the Galaxy Client.

Suggest searching the steam forums for non-GOG since that is the only other PC platform for NMS. However, since NMS does not use usernames you probably will also see your account name used but I am unfamiliar as to whether or not Steam will allow users to independently change their username.

Thanks to the both of your for replying to my thread.

However, the main problem is that I don't want to use my account name, as I want to be able and change it whatever I want just in game, not forced to my account name just for the game. :/

I just bought the game and I'm thinking about it. Will I be permanently assigned the current name from the GOG account in the game at the first login? And even if I change nickname in GOG, the old name will remain in the game?

No, if you change your name on GOG, your name in the game will change too, if you're using Galaxy. Be warned though that any discoveries you made and uploaded with your old name will still be attached to that name. New ones will be attached to your new name.