The libFuzzer website doesn't cite any supported platforms or platform requirements so I think this might just be a matter of someone putting in the effort. The Chromium documentation (where libFuzzer comes from originally) does make it sound like it either takes effort to integrate with various sanitizers or (more likely) requires the infrastructure that the sanitizers do. None of those support Windows and seem to work best on amd64 Linux or, if you're lucky, amd64 macOS.