You could fall back to a publicly available knowledge graph like Wikidata for your general-purpose "meta" concepts. Then Wikidata itself takes care of linkages at the "meta" level, while your own private information can of course still be managed locally.
It's an interesting idea. Maybe I should try. I suspect, though, that I want control over every node, no matter how general. The thing about my notes is they contain only information I think I might need. I have, for instance, an "emotions" node. I'm sure the Wikidata node for emotions is interesting, but I want my own node too.
I tried to square this circle once by writing Hode[1], which permits encoding certain data as relevant to me, and then filter my view accordingly when I wanted. But the encoding process (i.e. the user experience when adding data to one's knowledge base) was so hard that I gave up.
