To open any folder in a new window.

open_folder_in_new_window.py

import sublime
import sublime_plugin

class OpenFolderInNewWindowCommand(sublime_plugin.WindowCommand):

    def run(self, paths):
        if not os.path.exists(paths[0]):
            return
        self.window.run_command("new_window")
        window = sublime.active_window()
        window.set_project_data({
            "folders": [{ "path": paths[0] }]
        })

Side Bar.sublime-menu

[
     {
        "caption": "Open in New Window",
        "command": "open_folder_in_new_window",
        "args": {
            "paths": []
        },
    }, 
]