That’s not entirely true. Almost all inputs are in pixels, except maybe opacity. The input field I designated being faulty is the only one that has a percentage.
If it truly was agnostic, it would not be called letter-spacing, because in typography its called ‘tracking’ (not kerning, that’s for individual letters).
Almost everything in the screenshot is pixels.
The whole interface is based on pixels. The Rulers in Figma aren’t in CM’s or MM’s either, which would be a real drag for anyone using it to design a brochure, or print design.
So lets not pretend. Figma is mainly for web and thus in px and (r)ems.
PS: That’s why the fonts is also not in PT.