I hope this helps.
I was able to create it in a short amount of time because I had the basic scripts and information about Krita’s SVG processing that I had created and researched over the past few months. 
https://krita-artists.org/t/export-shapes-as-svgs-plug-in/92243
This resets the matrix translate component and translate parameter of the transform attribute of the exported SVG data, and sets the viewport centered on shape.
Only Text shape could not get transform atrtibute with toSVG(), so I workaround got it from matrix.