One thing to note is that hierarchical tags are supported in Obsidian. I believe the format is #big_tag\medium_tag\small_tag for example. I believe it’s a toggle in the Tags plugin settings whether or not to display the hierarchical relationship between tags in the Tags pane.
I don’t use tags a whole lot, but I do have those options turned on. It looks like this in the Tags pane, for example:

I know this isn’t specifically what you’ve asked about, but I thought it might possibly address some of your needs.