My use case would be more simple than others, but I am not super well versed in the actual current syntax of Obsidian. I like the idea of this syntax https://forum.obsidian.md/t/add-support-for-link-types/6994/... as it would be most flexible. But a simple [[Page Name]]{type:child} could be good, all I really need is a means of filtering linked documents by their link type (in a graph view/visualization) and ideally a method to query and display those. Dataview gives the second, though the first seems to require the link type to be a first class citizen.

I understand that it is a complex thing though, and not something easy to just throw in

you can use the supercharged links plugin and careful control of it's class types to achieve that, it's how I did it. I'm largely using schema.org types