In the string of images uploaded online, we get a look at file repositories, a rough map of the proposed Moon location, and shots of some early conceptual images and set pieces. As the story goes, CDPR originally intended for the Moon to be a featured location in the base game but recognised that it was too ambitious a goal, so they cut the content and instead decided to use it for an expansion – which ultimately never surfaced.
Cyberpunk 2077’s development has officially ended, so there’s no chance this will ever see the light of day.
The title suggests that there are files for an actual expansion, half-finished and unpublished.
Because that's exactly what this is. Click through to the source linked in the article, which is a 4chan thread. It's quite a bit more than just concept art, there are actual world map files that were extracted. The files, themselves, aren't made available, but the OP of the thread posted several screenshots of these assets rendered in-engine with a dev build of the game. There appears to have been quite a significant amount of development that was put into this unused area of the game.
Those are still what I would consider "sketches". Just not the two-dimensional kind.
There are a couple more detailed assets, but tubes and boxes laying out locations, interiors and buildings is something you do when still exploring ideas and don't want to lock anything down.
The written material suggests the writers got the furthest into it. But this is very much planning, not production.
It also says that they might have planned a second expansion featuring it. Doesn't really say when the content was made, just that it would have been DLC.