Maybe the only way is to screenshot the Project Hail Mary credits when it comes to streaming.
It sure sounds like you value his work at less than a dollar per image. The desktop-background market may not be something he's interested in.
> Maybe the only way is to screenshot the Project Hail Mary credits when it comes to streaming.
...and this may be the reason he's not interested in the desktop background market. You make a single sale, and the image is trivially reproduced. Doing it for pennies is not a winning proposition; prints have better margins.
If you want pretty and free nebula pictures, you can have Generative AI make as many as you like - if you want his work: you'll have to abide by his terms.