Toybox

Toybox is a free and open-source software implementation of over 200 Unix command line utilities such as "ls", "cp", and "mv". The Toybox project was started in 2006, and became a BSD-licensed BusyBox alternative. Toybox is included with Android 6.0 "Marshmallow" and all later Android versions (i.e. on all currently supported Android versions), and also used to build Android on Linux and macOS. All of the tools are tested on Linux, and many of them also work on BSD and macOS.
Functionality and aim.
Toybox aims to provide a BSD licensed replacement for the GPL licensed BusyBox.
Toybox's major technical design goals are simplicity, smallness, speed and standard compliance. Toybox aims to be mostly POSIX-2008 and LSB 4.1 compatible, and doesn't focus on having every option found in GNU counterparts. 
Toybox is licensed using a permissive BSD license, where BusyBox uses the copyleft GNU General Public License, which led to different usage domains. BusyBox is mostly used in the copyleft FOSS domain, while Toybox is used mostly with permissive licensed projects and by commercial companies, e.g. Google's Android, which is an explicit target of Toybox. Feature-wise, Toybox has not reached parity with BusyBox.
History.
Toybox was started in early 2006 by Rob Landley after he ended his BusyBox maintainership due to a dispute with Bruce Perens, the original creator of BusyBox. In 2008 the project went dormant.
At the end of 2011 Sony employee Tim Bird suggested creating a permissively licensed alternative to BusyBox. Rob Landley agreed with this goal and resumed work on Toybox, starting by relicensing from the GNU General Public License to the 2-clause BSD License. In March 2013 the project was relicensed to an even more permissive 0-clause BSD License.
At the end of 2014 Toybox was integrated into the Android 6.0.x "Marshmallow" development branches for use on devices. In 2018 a host Toybox prebuilt was added to AOSP to help make the Android build itself more hermetic.
Controversy.
In January 2012 the proposal of creating a BSD license alternative to the GPL licensed BusyBox project drew harsh criticism from Matthew Garrett for taking away the only relevant tool for copyright enforcement of the Software Freedom Conservancy group. Rob Landley, who had started the BusyBox-based lawsuits, responded this was intentional, explaining that the lawsuits had not benefited the project but that they had led to corporate avoidance, expressing a desire to stop the lawsuits "in whatever way I see fit".
Project progress.
The official Toybox documentation lists an overview of the available, partially available, and missing commands. As of May 2020, Version 0.8.4 achieves approximately 80% of the project's implementation goals targeted for 1.0.