Tracing could be easily implemented using third party libraries [2]. Custom extensions would be initially limited to the "Generators" panel. I haven't thought about the live path effects yet.
The hardest part remaining is full support for filters, but I have this feature mostly sorted out in the dev branch and the UI is going to be much nicer than in Inkscape [3][4].
[1] https://i.imgur.com/e08OW5x.png
[2] https://boxy-svg.com/ideas/5/vectorize-generator
Inkscape 1.0 adds what’s basically a more powerful version of that, a pressure-sensitive pencil, implemented with the powerstroke live path effect—more powerful, I say, because it’s editable, because it’s not immediately flattening it to what SVG can represent, but is also keeping its own editor information in namespaced attributes. That’s how you can add things like that and mesh gradients before SVG supports the concept.
I’m still intensely sceptical of your claim of full feature parity with Inkscape in a year, but I’ll believe parity for >95% of users and use cases.
My biggest problem with your app at the moment looks to be that path editing is painful compared with Inkscape. I like to show the outline of the path, and its keyboard and mouse operation also feels just all-round superior at present, and I don’t think that that’s just my greater familiarity with Inkscape showing through.
I’d also like more text labels and fewer icons. Iconless labels have no place on something like your filters panel; text labels are objectively superior. I’d say similar for the Defs panel and other such panels.
I wish you joy!
There should be an outline shown when you hover a path with the "Edit" tool [1], though it's a bit sloppy and needs more optimization. Most path-related commands are exposed by the "Shape" panel. To convert a node between a smooth and an edge type you must double-click it. The ability to box-transform selected nodes and to move them with arrow keys is missing but should be added soon.
My main problem with text labels is that they take a lot of horizontal space. Text labels could be shown only when the panel is wide enough to fit them, or when user hovers the icon (like it's done in Autodesk Graphic).
Not everything is possible this way; mesh gradients can’t be emulated in vectors, for example—though you could effectively implement a canvas-backed renderer for it to polyfill it; but a lot of functionality can be implemented without upstream support.