[[ ]] creates out-links to other pages of your vault (global links).
There could be an option to create in-links (local links) within a canvas, maybe using a special syntax.
How this could work
You can mark entities within the canvas as targets using a special syntax, maybe in the same way you can mark blocks as targets within notes. Then, just as you can turn any text into an out-link, you have the additional option of turning it into an in-link.
This would allow you to create a structure for navigating a canvas (eg table of contents, or link to an area where you expand upon a concept).