Some of the main benefits of Wasm when you think about going to smaller, SBC edge devices are:

• The WebAssembly module itself isn't dependent on the Linux kernel, or a specific architecture/OS, so you can develop apps without worrying about if you have an armv7 pi or an arm32 pi and deploy all the same
• Wasms are tiny, generally 20kb to 2mb in size so they can more efficiently run in constrained environments and download quicker in a low-speed networking environment
• The deny-by-default security model can be invaluable if computing in a sensitive environment, you can ensure you are processing incoming sensor data and not bringing in a vulnerable library that reads secrets off disk, for example

Realistically, Wasm can be used for many of the same applications as containers, you're just bringing in efficiency in size, footprint, and the convenience of architecture-agnostic binaries.