Akira is an open-source UI design software project that's looking for help getting development started on Kickstarter. Consider donating.
I spend every day with design files and while Figma is an incredible achievement, using a browser for complex designs can be difficult. On Windows, you can use the Adobe suite; on the Mac, you have access to Sketch, the Affinity Design suite AND the full Adobe suite. On open source platforms, not so much.
There are programs currently available for open source operating systems, like Gimp, Inkscape, Krita and others on Linux and BSD, but they aren't focused on UI design. Of all the designer/developers who run Linux that I know, they get by either running Photoshop in a VM, or using web based tools. Having a fast, native and modern design tool be accessible to all can only be good for the future of design.
I mean, how many of this last generation of designers got their start using bootlegged Adobe software? Wouldn't it have been better to have gotten our start using applications that were not only free to use but could contribute to its development?