Yes, exactly. In principle, Logseq’s data model already supports all of this. All we need is to give every tag page a couple properties (related, narrower, broader etc.) and this is all there is to it.
What is missing is a way to traverse the properties and display the results as a browsable tree.
@alex0 wrote a proposal to do so.
Ultimately some other UI/UX features would be nice, e.g. a way to easily access broader/narrower/related items, a tree view in the sidebar, a way to efficiently manage tags etc.