Hash in menu item url are removed when displaying the menu on a page

If a menu item has a submenu and I specify the hash symbol (#) in the Link field of such parent menu item in the admin panel, I receive empty url at the frontend and therefore if click by such link, I follow to the homepage.

Even if I use in my menu--main.html.twig template the code like

{% set menu_item_url = item.url %}
{% if menu_item_url == '' %}
{% set menu_item_url = '#' %}
{% endif %}
<a href="{{ menu_item_url }}" ...

I still receive empty href=""

How to resolve the problem? I mean is there a way inside of templates? Of course, I know that I can resolve the problem with JS.

Note: I don't mean an anchor, I just need # as parent item url if the item has a submenu.

Here is an example, where clicking 'Example menulink' will not send you elsewhere is you have a submenu item. Otherwise use url: 'internal:##'

MYMODULE.menuitemxyz:
  title: 'Example menulink'
  url: 'internal:#'
  menu_name: mycustom-menu
  weight: 1009
  enabled: 1
  expanded: 1

MYMODULE.menuitesub1:
  title: 'Anchor link'
  parent: MYMODULE.menuitemxyz
  menu_name: mycustom-menu
  url: 'internal:#using_anchors'
  weight: 1007

If you do not want a link in the parent menu item, you may also use <none> as link. I always use it for menu items without a link.