ONNX is a format. There are different runtimes for different devices... But I can't speak for any of them. > specific instruction sets like for apple silicon

ONNX is a format. There are different runtimes for different devices... But I can't speak for any of them. > specific instruction sets like for apple silicon You are thinking of the Accelerate framework support, which is basically Apple's ARM CPU SIMD library. But Llama.cpp also has a Metal GPU backend, which is the defacto backend for Apple devices now.