With the "fun" to rewrite all WebGL shaders into WGSL.

You can use the SPIR-V compiler toolchain to just transpile from GLSL to WGSL :)

Minor nitpick: this translation happens in separate libraries/tools which just make use of the SPIRVTools library for some SPIRV processing tasks, but not the actual translation to WGSL.

Tint (Google, implemented in C++): https://dawn.googlesource.com/tint/

Naga (Mozilla(?), implemented mostly in Rust): https://github.com/gfx-rs/naga

Both are a bit similar to SPIRV-Cross, except that they also support WGSL.