Is there any known thread for media sharing? I didn't find any
If I were you, I'd post a thread here and in the general forum for Galaxy 2.0 box arts. I'm saying create two threads in two different locations in case this subforum gets archived or worse, removed. The general forum will always be there, ~~so long as gog doesn't delete their forums entirely.~~
In addition, I'd host the box arts on somewhere resilient and have backup links to them. Good luck!