Hi, I would like to ask, if it is possible to see my friends' achievements in GOG. We both own the same game (The Witcher 3), and we would like to see our activities. I was not able to find it anywhere though. Thank you for response.

Player profiles have not been implemented so far.
Might be in the future but who knows.

Gog already have the data on their servers, I got my achievements displayed correctly in new galaxy install (when I was trying dualboot win10). it's only matter of how high priority is given to implementing it. With how fast they fix their website... my estimate is "somewhere within 20 years from now".

Not currently however GOG just stated recently that the next update of Galaxy will add the ability to see friend's game play time. I'm not sure if they mentioned whether that will also cover achievements or not, but if not then I'm sure that will come at a later date as well. With very few exceptions though they don't give estimates of when a given feature will be available unless they're practically about to release it within a few weeks though, so we just have to wait it out.

No doubt features like this are the beginning stages of having user profiles.