Some feedback that's hopefully helpful, would be great to add to the readme:

What would you say the primary purpose of this tool is? (not that a project needs a purpose beyond "because it was fun" or "just to learn" or even "because I could", but wondering). I have many times wished for a png to svg converter for various reasons (size, hackability, animate-ability) but I struggle to understand why you'd want to go from png to png with this (like in the demo image). I could very well be missing something though. The readme doesn't mention svg at all, though the linked inspiration project does so I assume that's a possible use case?

This page is a little older, but it offers the same kind of service and allows you to save in svg format : https://www.samcodes.co.uk/project/geometrize-haxe-web/

Not the guy who made it but I immediately wondered if I could use the intermediate steps with some "outline" mode to help me see things in shapes and finally learn to draw a bit.