Hi.
Thank you for your answer.
In the past, I have created and published several free games on itch.io, and one fixed-price game for now.
I take care to respect the licensing of the illustrations I use, and I never used AI-generated images.
I do not have any use in mind for now for those nice sci-fi illustrations you shared, but I collect many Creative Commons or public domain illustrations on this page, for later use in game projects: https://chezsoi.org/lucas/blog/pages/images-libres-de-droits.html
As you may already know it, there is another Creative Common license, CC BY-NC, that explicitely allows reuse of material but forbid commercial use : https://creativecommons.org/licenses/by-nc/4.0/deed.en
I collect illustrations under that license (and CC0, CC-BY...) so that I can use them in the free games I create (but not in the fixed-price games, of course). However I never use images under CC BY-NC-ND, as this license makes it impossible to use them in free games published online.
Of course CC BY-NC-ND licensed illustrations can still be used by TTRPG game masters for their own private use in their game sessions. And I totally respect that as a choice for an illustrator: reuse is restricted but it is always very generous to share illustrations online with a community of enthusiast gamers.
Thank you for your time, and thanks a lot for sharing your work with us sci-fi fans! 🙂