After weeks of deliberation, experimentation, and reflection, I've decided not to use Figma to house my contributions to the Godot Design System. There are many reasons to favor Figma over Penpot for this massive project, but ultimately the spirit of FOSS is a core principal of both Godot and its community, and introducing a hard dependency on a closed source proprietary platform for the Godot Design System would be, in my view, a weak decision.
For anybody interested, Aaron Mahlke built a project to begin exploring what Godot in Figma would be like -- it includes a very cool proof-of-concept prototype!
There are indeed a select few noteworthy advantages for using Penpot over Figma, which include:
Just to be very clear: Figma is currently a much more productive piece of design software than Penpot, and the comparatively massive familiarity that most professional designers have using Figma isn't trivial. I've swallowed the pill and accepted the hard road, with the experience to know what that means. If truly show-stopper issues arise (e.g. massive data loss, library corruption, etc), I might have to reassess this path.
I will be updating progress in this issue regularly. Ideally, I will earn the right to create and manage this as a Project in this repo, which would also be useful to help identify areas where other contributors can tackle specific todos. Alternatively, new "penpot" and "design system" labels could be created and used to help track issues. That said, I believe that a lightweight project management prioritization system could help with various things, like isolating design requirements that are blockers for issues or active PRs in the Godot Repo. Otherwise, we could simply use "high priority" and/or "blocker" labels to isolate these issues. However, some designers might not be as comfortable navigating Github as the usual Godot contributors, so I believe a project board could be useful.
Link to the Godot Design Penpot dashboard -- currently requires permissions to access.