If you watch today's Fedora Design team call , you'll hear and see a little discussion of a new open source UI wireframing and prototyping tool called PenPot. It's created by the folks who make Taiga, which is a tool we've used in Fedora before. It is a hosted, browser-based app that runs great in Fedora, and you can check it out here:https://penpot.app/
I am trying out this tool to wireframe the redesign for the main Fedora website and create formal brand guidelines for the new Fedora logo. I set up a Fedora Design team on the main server at penpot.app. If you would like to join this team, let me know :)
Note this tool isn't meant to replace our usage of Inkscape, especially for illustrations, logo designs, print layouts, etc. But it is a very well-designed tool for UI mockups so I personally will be testing it out more for Fedora UI mockups.