The export persona only exports to raster (bitmap) files, not vector of any kind (to include SVG). I'm using Silhouette Studio Designer with a Silhouette Portrait cutter. Today is my first day starting to sort this out. I ended up taking the objects I wanted to cut and placing them in a new file. Then did a combine to eliminate interior lines (tried without doing that and the Silhouette software cut all lines, essentially segmenting my piece.
With the new SVG eliminating the interior lines, the Portrait cut out my object from card stock (for practice). I think it's only 80 lb so thee was some fuzzing at the cut. Once I sorted out the cut depth, things are looking pretty good. Tomorrow I'm going to do some vinyl cuts.
In a perfect world, Affinity Designer will allow me to select an object or objects and export them to an SVG file which with a page size that is only big enough to hold the exported object(s). I'd also like to see some kind of "print selected" functionality that would only send the selected object to print.