wl-clipboard

https://github.com/bugaevc/wl-clipboard

This project implements two command-line Wayland clipboard utilities, wl-copy and wl-paste, that let you easily copy data between the clipboard and Unix pipes, sockets, files and so on.

pass password manager does rely on wl-clipboard in a Gnome Wayland session

Is it open source? Yes
https://github.com/bugaevc/wl-clipboard/archive/refs/tags/v2.2.0.tar.gz