Addition of stdin support [CLI]

Could you please add the support for stdin just like the MPV/VLC one?
https://mpv.io/manual/stable/#configuration-files "One exception is the lone - (without anything else), which means media data will be read from stdin"

Atm if I try to pipe any URL it just returns a "Failed to render the file" error, tho it actually works fine if I input the URL by MPC-HC GUI.

The player has full command line support. It also already supports pipe input from stdin. But you need to pipe in actual file data. Not just an URL.

You should use normal command line instead:
mpc-hc64.exe URL