Filter for unlinked references, not just for linked references

I’d like to see an option to filter for unlinked references as well.

Imgine you do research, and you have a page open with the name of 1 source.
I like it to write my notes to a source in the same page.
To link my notes to a specific pages:
If i do write in one note something about memory, i would link that via Tag or Page Link to a page called “Memory”. But if in the same note something else is mentioned for example ''Alzheimer" but for me it’s not enough relevant to show this note in my linked references in my “Alzheimer” Page for some reason, i still would like to filter in unlinked references to explore unknown relations.