It is inaccurate to call things like threading a Wild West of implementation-defined stuff. It is true these things aren’t de jure standard, but most important

It is inaccurate to call things like threading a Wild West of implementation-defined stuff. It is true these things aren’t de jure standard, but most important stuff has de facto standard portability libraries in Common Lisp. For threading, use BORDEAUX-THREADS. For filesystem operations, use UIOP. For module definitions, use ASDF.