First suggestion here;

I'd be nice to still be able to see the statistics on the grid based view off the games in your library, they are a nice addition compared to most other clients on the detail off them. Like achievements percentage and the other.

In the image attached I gave a little example of what could happen on the clicking / hovering over the game.

This can also add some nice additions of a custom color code to customize GOG Galaxy 2.0, both background, the layout of the Play button, whatever else you can do there.