It would be nice if we had one of those, but SVG is not it, at least not unless you’re willing to gloss HTML as “an open format for rendering reflowable text”. SVG is a full platform for web applications with fixed-layout graphics and rich animations, essentially Flash with worse development tools.
There have been some attempts to define a subset of SVG that represents a picture, like SVG Tiny, but that feels about as likely to succeed as defining JSON by cutting things out of JavaScript. (I mean, it kind of worked for making EPUB from HTML+CSS... If you disregard all the insane feature variation across e-readers that is.) Meanwhile, other vector graphics formats are either ancient and not very common (CGM, EPS, WMF/EMF) or exotic and very not common (HVIF, IconVG, TinyVG).
(My personal benchmark for an actual vector format would be: does it allow the renderer to avoid knowing the peculiarities of Arabic, Burmese, Devanagari, or Mongolian?)