Spack is a package manager designed for high performance computing (HPC) that supports multiple versions and configurations of software on a wide variety of platforms and environments. It reduces the complexity for software installations on exotic architectures. In short, you can manage tricky installations with simple syntax (see also https://spack.readthedocs.io/en/latest/)
An example of usage at the Pawsey Supercomputing Centre is to install packages that require specific optimisation for performance, as opposed to use of generic containers. The Spack-installed software can be invoked by calling the executable with the full path, using spack load, or by generating a modulefile with Spack and using it.