Kongruent is a language and compiler for data-parallel programming aka shaders. It compiles Kongruent code to its own bytecode and can then transform it into HLSL, GLSL, MSL (for Metal), WGSL (for WebGPU) and SPIR-V.
It is Robert's successor project to https://github.com/Kode/krafix which includes earlier work by Robert and Bill who later contributed HLSL and Metal support to SPIRV-Cross.
Kongruent integrates deeply with Kore 3 (see https://github.com/Kode/Kore/tree/v3) and a bunch of samples can be found at https://github.com/Kode/Kore-Samples/tree/v3.