Hello,
Is there a reason why -unix flag is disabled on Windows? As I understand, this kind of support for local sockets was added in Windows 10, somewhere in 2018. Recently, I have cloned the project and allowed the flag and its usage in a custom build. The application behaves correctly and bin\go_build_main.exe -plaintext -unix "*.sock" list (also the direct method calls) work as expected.

The only change I have applied is to add windows target to the +build in ~\grpcurl\cmd\grpcurl\unix.go:

// +build darwin dragonfly freebsd linux netbsd openbsd solaris windows