Jon Rohan writes on the GitHub Blog:
To support your project’s contributors it’s important to make the contributing experience as frictionless as possible. Migrating our Octicons to Figma let us cut out painful steps in our previous workflow. Having their API available for automating the work has allowed contributors to contribute using powerful platform-agnostic design tools without any overly complex setup.
This seems to be one of the first major steps I've seen to use a platform-agnostic design tool like Figma, which lets you design, prototype, and gather feedback all in a browser based design tool. Couple that with a robust API and some robots to automate things as well as open up your design flow to contributors.