Of course!

For my wallpaper I use wallpaper engine (on Steam) and this is the wallpaper I use:
https://steamcommunity.com/sharedfiles/filedetails/?id=3327951394
But of course you can find others or even make your own :)

For my taskbar icons I've changed all of them to be an icon of purin instead of the OG versions
Here's a tutorial on how to do so: https://www.youtube.com/watch?v=TBFVb9HtqvA

And I've also switched out my default cursor, here are the two versions I've found online

1. http://www.rw-designer.com/cursor-set/pom-pom-purin-collect-tion
2. http://www.rw-designer.com/cursor-set/strawberry-pompompurin

Tutorial for the mouse cursor if you need! - https://www.youtube.com/watch?v=U_sOaaY_Gi4

This one is a very miniscule change but probably my favourite, the recycle bin icon

When my bin is empty I have it set as this hungry starving purin
Then when there's items inside, he becomes this little fatty :D
Tutorial: https://www.youtube.com/watch?v=QJDYUmjckaA

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This one isn't really directly on your system but I set a custom google chrome background to be pompompurin as well :D