I see now such an UI element for breadcrumbs already is implemented, in side-by-side view:
While redundant now, this UI could be used also in column view. It is more readable because text is not vertical.
By the way, what do you think about the macOS Finders list-view? It is very useful for some things, in that you can expand
folders and see folder-contents in a nested way. It is possible to select files from multiple folders and operate on them
simultaneously, which is very nice. I understand this would be a big undertaking to implement. But macoS has it, and
OneCommander is the defacto Finder replacement at the moment. :-)