Toybox, Clang/LLVM, Musl, is an obvious distro core made up of permissively-licensed components. (Busybox, as used in many distros like Alpine, is GPLv2.). Source: over 2 years ago

> Toybox's main goal is to make Android self-hosting by improving Android's command line utilities so it can build an installable Android Open Source Project image entirely from source under a stock Android system. -- http://landley.net/toybox/about.html. - Source: Hacker News / over 3 years ago

README doesn't explain what it is beyond "all-in-one Linux command line". Here's the about page: http://landley.net/toybox/about.html (including comparison to busybox). And here's the list of commands currently supported: http://landley.net/toybox/status.html. - Source: Hacker News / over 3 years ago

For #1, you can just put #!/bin/bash at the top of the file to use Bash. Bash is still available, it’s just not the default for scripts that specify #!/bin/sh. #2 is still currently tricky, but Rob Landley (former Busybox maintainer) is working on a full bug-for-bug compatible Bash clone called toysh which will be included in an upcoming release of Toybox[1]. Once that’s released, I’m looking forward to... - Source: Hacker News / about 4 years ago

My advice is, when you feel you need that challenge, install DOSBox or DOSBox-X and Open Watcom C/C++, DJGPP, or gcc-ia16 and do some retro-programming. You'll also get the fun of being able to do low-level hardware twiddling and rely on DOS being so simple that it's effectively an RTOS. Source: about 2 years ago

And, if that surprises you, gcc-ia16 is a thing that has come into existence not only over a decade after DJGPP but also after Open Watcom already existed. Source: over 2 years ago