When I try to view my or anyone else's profile I get
"Access to www.gog.com was deniedYou don't have authorization to view this page.
HTTP ERROR 403"
Did you try to look at the accounts while being logged off?
That may be a reason.
If so - try again, while logged in. (also: see attachment)
Also I wanted to know how the achievements work for GoG, but there seems to be no information for that. I'm interested whether they are public (like Steam) or private (like Blizzard).
I don't use Galaxy (which, to my understanding, is needed to make use of achievements (other than pure in-game achievements))
, so I can't really help you there.
Maybe Galaxy has a feature to set your achievements visibility to either "public", "only visible for friends" and "private - only I can see my achievements"?
Comparable to how you can set the visibility for your account/wishlist? (also: see attachment)
Also for some reason my GOG avatar is not visible here in forums.
Did you change your avatar very recently?
That could cause that.
It can take a few hours until the new avatar shows in public. (also: see attachment)