One more software system designed to be minimalist: https://minimacy.net/
There are many ways to be minimalist because there are so many criteria that can be minimized. This one aims for minimal total code complexity within the constraints of being useable for a specific category of code, which is roughly a single server or desktop process. Minimacy is a programming language (strongly resembling the ML family) plus a virtual machine that runs the compiled code. The VM can run on bare metal, or as a process in a host OS. Development happens outside the system. The whole system wants to remain undertstandable in all detail by a single person. So far that's guaranteed by having a single author.
I attended a seminar by it author yesterday, where he discussed many of the tradeoffs made. Sounded quite reasonable.