Part of why I gave up on doing more work with vectors was because of my frustration with the default SVG export settings in Affinity Designer. I couldn’t get them to work properly with other programs and didn’t realize what I was doing wrong until fairly recently.
One of the selling points of Affinity Designer is its ability to mix vector and raster graphics, however if you want an SVG to work properly in other programs and to be fully SVG any raster elements have to be removed.
Another thing to bear in mind is that elements shouldn’t be grouped or in nested groups before exporting SVG files for use in other programs to make them as compatible as possible.
Strokes on all the elements must not be using raster based brushes, so setting them to basic settings is a good idea. The style panel is useful because you can save a set of basic styles to use on everything.
It is also a good idea to convert everything to curves first (like ellipses and text).
I also had to customize the export settings like so or it would put each vector curve in a group on export for some reason. I think the flatten transforms solves that issue.
I finally worked out how to use the export persona as well. It is very useful for quickly exporting multiple layers as slices.