Something like this is probably better suited toward a specialized text expansion program (I use aText, somewhat arbitrarily). This are going to be more fully featured than Obsidian could realistically be without taking time away from developing other features.
I have a few useful shortcuts already set up. Besdies xdate (which would be replaced with 2020-05-27, or xday (Wednesday, May 27, 2020), I also have xz set up to replace with [[(contents of clipboard)]], so I can highlight text, press CMD-x to copy, then press xz to insert it as a link.