That solves a different problem. REM is useful for making the value relative to a master value; v-units make the value relative to the viewport.
I actually use the two in conjunction. I set some my html {font-size: 1.2vw;} (or whatever), and all type in the document to 1rem (or whatever measurement). Then I finally step out the html size to major browser breakpoints using old-fashioned media queries.
I can’t share my recent stuff because it’s still under private development, but here’s the results of my first experiments in this method, a little rough around the edges but etc.
