The "official" wasi-sdk is quite similar, a prepackageded clang toolchain to compile c/c++ code to wasi. What makes emscripten more complicated is the browser integration (eg compiling into a ready-to-run html/js/wasm bundle and providing C API wrappers for various web apis), and Zig also only manages the "compile to wasm" part but lacks Emscripten's JS interop features (that's why in my zig+wasm experiments I use the Emscripten SDK as sysroot and linker).

What the Zig toolchain provides that neither the wasi-sdk nor emsdk have is a package manager and build system which are both much nicer than what the c/c++ ecosystem offers.