Hello!
That's an interesting project. Unfortunately the site you linked doesn't load for me. I'd have loved to see it.
Ofcourse, you can use the sprites in any way you wish, since they're CC0. If you want to give credit, then yes, use my itch username. My nationality is bulgarian. The sprite names might be a bit too long, if that's a problem you can shorten them to the 1-2 most important keywords.
I'm glad you like and appreciate my work. Good luck with your project! ❤️
P.S. thank you for the generous donation!