Convert PSD to json (svg format)

You can not really convert a Photoshop raster image layer into a vector file format. A photoshop Raster can also filters  and adjustment. There are also Smart object layer how do you add one toe a svg with text the represent a raster layer i would bet.   If you have a Photoshop  document that contains only vector layer I would think the Export as svg will create a svg image file that contains all vector items.  If  there were raster image layers and smart object layer and layer styles I would expect the SVG file will contains some text encoding of Photoshop Image Pixel data. Text and Shapes layer will have vector path and other encoding in the svg.  Photoshop is not a vector editor. Photoshop does have some vector tools.   Many file type are text files.  SVG are text files  HTML are text files.  Photoshop JavaScrip jsx file are text file,  json files are text files.  However the text in each is processed by a diffent sets of rules differently.  So json and svg are text files the  encoding|language|sysntax|Markup what ever you want to call it are not the same.  A json script should be able toe read a text file  like an svg  processing the would be quite and undertaking.