Hi
You should be able to export vector layer(s) to SVG I think…
The simplest thing I think is to unzip krita file (it’s a zip file) and get the SVG files (one per layer) and then, import SVG files in Synfig.
Or (especially if you have text in vector layers) to use the snippet written by @wolthera to extract svg files from krita files:
Or, if you only have one vector layer, just select all shapes in layer and do copy/paste
Grum999