Thanks for asking!
The desktop theme is my creation - usually used with visualprefs, sadly VP doesn't work properly on CSPPC accelerators (it hangs upon opening the workbench). At some point I was making desktop themes for the Amiga - you can find some of these on Aminet, others ones are unreleased or owned by another OS. They also were distributed on a website called Overshaker, that may or may not be on the wayback machine. I wanted to bring it back up yet found another Amiga desktop themes dedicated website and cancelled that rebirth.
A few of my desktop themes are pretty dark, made for very bright displays, very much akin the desktop of that recent "Amiga computer" released by AmigaKit.
The icons aren't mine though, I did convert a bunch of those from a street art styled artist that I really love, Mattahan. He made icons for PC, Apple, Amiga and some more OS... I believe there's a page with his artworks on DA. Google search "Mattahan icons" you'll find a bunch of his stuff. I've tried to contact him about releasing a pack with my icon conversions/updates and newly created icons based on his work but never had any answer. My version looks great on 800 up to 1600px wide screens, rescaled and redrawn whenever necessary since his icons are either too large or too small for my tastes.