There is a project called “AnyType” that is real and i use it but it’s “open source promised soon”. The gist of it is a Person knowledge management system except the items are in a linked graph (and the relationships are typed).

It actually has an editor that looks eerily like the linked one so I wonder if they’re related. It lets you use slash-commands that’s much more expressive than everything except maybe notion. But again, it lets you operate against a database-like set of objects.

I don’t think you can point it at real databases though.

AnyType.io