Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
Pies is a Python 2 and Python 3 compatibility layer with the philosophy that all code should be Python 3 code. Starting from this viewpoint means that when running on Python 3, Pies adds virtually no overhead. Instead of providing a bunch of custom methods (leading to Python code which looks out of place on any version), Pies aims to backport as many of the Python 3 API calls, imports, and objects to Python 2 as possible, relying on special syntax only when absolutely necessary.
musl is a new implementation of the standard library for Linux-based systems. It is lightweight, fast, simple, free, and strives to be correct in the sense of standards-conformance and safety. It includes a wrapper for building programs against musl in place of the system standard library (e.g. glibc), making it possible to immediately evaluate the library and build compact statically linked binaries with it.
The Linux From Scratch project is intended for Linux users who want to build their own custom Linux system. Reasons for wanting to build such a system are diverse. Perhaps you want to get into more detail as to what happens behind the scenes. Perhaps you are fed up with the bloated standard distributions. Or perhaps you don't want to rely on pre-compiled binaries out of concerns for security.