Back last year Apple started discontinuing support for Python in OSX. Now, as of Monterey 12.3, Python is no longer shipped with the OS. There *is* a python3 exe in /usr/bin but that’s as far as it gets – no framework to build/link to.
So as of now, the Mac version of Glade ships with its own Python framework. So you don’t need to install Homebrew or any other python distribution (unless you want to). This is in fact similar to Windows which also ships with its own Python installation, as Windows never did ship with Python.