Update:
Thanks for all the suggestions, folks!
Before, my desk felt super cramped — monitor and laptop taking up half the space, PC stuck awkwardly on the left（Before desk setup). It should be noted that the thing that looks dirty is actually a soft wrist rest, not a keyboard.
After adding a stand and moving the PC to the right, it feels way cleaner and way more open. Now I can even stash my mouse and KVM under the shelf. Night and day difference. This setup is great! Thanks again for the tips.