The Angular team hasn’t published what exact design tool was used for those specific SVGs and they don’t provide the original source files like .ai or .fig for assets in the repo. In practice, teams at Google typically use a mix of tools such as Figma, Adobe Illustrator, or Sketch to design vector assets, and then export them to SVG for use in the codebase. Since the SVGs are already in the repository, the intended workflow is to treat them as the source of truth rather than request the original .ai files.

If you want to work with or modify them, you can safely import the existing .svg files directly into Figma, Adobe Illustrator, or Inkscape and continue editing them there. All of these tools support round-trip SVG editing very well.

So the practical answer is: you don’t need the original .ai files. Just open the existing SVGs in Illustrator or Figma and you will be able to inspect and modify the layers, paths, groups, colors, and exported structure easily.