Unable to identify a nav_menu_item by slug

I can’t identify nav_menu_items to properly format them with a different icon each.
Using an ID-based class is not an option since all sites use the same template and same main pages.

I can set a DIFFERENT slug for the nav_menu_items, but not the same (it seems wp core is not ready to keep them apart from the actual post safely, yet)

I tried using menu_order, but it’s not safe.

Adding classes to the menues won’t export to the other blogs when exporting the pages (I’ll make a set of master pages in one site and then export them to the others)

Could you please, since using the same post_title or post_name is not an option, make a new function to add the post_name to the li class, somehow?

Thanks.