McKinley is a Mac app for designing your own SF Symbols — with a vector editor, SVG import, searchable symbol libraries, nine point-compatible weights, colour rendering modes, and a live preview powered by Apple's own renderer.
Have you ever had the SF Symbols app reject your SVGs because the different paths in your different symbol weights were not in the same order? Or didn't have an identical number of points? Or you'd forgotten to turn your strokes into outlines?
I have. I got annoyed. And I solved the problem by building the tool I wished existed! (Because there's no solution like spending three months on a side quest building a vector graphics editor, right?)
Anyhow, enjoy McKinley!