Bethesda has just released its big expansion to Starfield called "Shattered Space," and judging by the review scores from both critics and players, the reception hasn't been promising and is certainly an indicator of underwhelming sales figures.
While there aren't any official unit sales out for Shattered Space, we can devise an idea of how the title is performing by looking at a few public metrics. Firstly, when Shattered Space was released on October 1, the concurrent Steam players peaked at 21,792, which is only an increase of approximately 6,000 players from the title's previous concurrent player high back in August. What paints a bleaker picture is Starfield's concurrent players peaked at 330,723 when it launched in September 2023.
Another indicator of Shattered Space's sales performance is Starfield's position on the Most Played Xbox Games list, where it is ranked number twenty-six. Moreover, Starfield is currently the seventh most-played game on Console Game Pass and fifth on PC Game Pass, which puts it just behind the Microsoft Solitaire Collection. Moving back to Steam, Starfield is directly competing with Fallout 4 on Steam, a Bethesda title from nearly nine years ago.
Judging by these player figures, it doesn't appear that there is much initial interest in the Shattered Space DLC, and perhaps the best indicator of that interest is the number of people playing the title on Steam. A good comparison of interest being fulfilled with a DLC would be the release of Cyberpunk 2077's Phantom Liberty expansion, as that caused Cyberpunk's concurrent players to jump from 32,178 to 259,283.

Cyberpunk 2077 Steam charts