KiCad is used for electronic design, while STEP is a standard format for exchanging 3D CAD models.
The viewers are written in Bend, described in the repository material as a massively parallel functional language. Their stated design goal is to preserve object identity across repeated runs: a reference to a particular object should continue to resolve to the same geometry. The supplied example is a reference to pad 14.
The material describes viewers rather than a text-to-CAD generator or a general-purpose CAD authoring tool. It does not establish a release version or date for the viewers, performance characteristics, supported KiCad or STEP variants, licence terms, installation requirements, or production-readiness claims.