Ha! I wrote the first commit to CoreOS's toolbox in 2014: https://github.com/coreos/toolbox/commit/dc4aa0b14bceafd6afa...

And then I read your comment and my first reaction was, oh, they typoed toolbox. But, nope, Red Hat created toolbx which confusingly has the CLI binary of `toolbox`: https://containertoolbx.org