Turns out, Wayland has wl-copy:

https://man.archlinux.org/man/wl-copy.1

(i was also interested :)

I have a few scripts that interact with wl-copy. Like one that just cats all the files in a directory and pipes it into wl-copy so I can paste it somewhere else. Something like that would've been immensly useful when I was still on windows, but that would've been too much a bother to set up.