I think what is nice about this project is that it combines everything in a mono repo which is nice for setting up continuous integration and other testing workflows. This project can be used to build toolchains for newlib (bare metal), musl and glibc. It also will allow building qemu and spike (instruction simulation) simulators to allow running RISC-V code without special hardware. It can then run each project's test suites as well as it has some integration tests (dhrystone).
This repo will be useful for getting started with toolchain development. If you are just a user wanting to write c/c++ app code then use your distro's toolchain packages.