You don't need your language/runtime to support arm/other to run same compile artifact on arm32, arm64, power5 and amd64 - compile to wasm once, run anywhere (nginx unit would still need to support your target).
Your runtime theoretically don't need is support - compile to wasm, run on FreeBSD/arm.
You can compile your c microservice to wasm, and your rust microservice, and your c++ microservice to wasm - and deploy them sandboxed via the same stack - reducing complexity (note that another option is to deploy via nginx unit - different way to reduce complexity).
You don't need your language/runtime to support arm/other to run same compile artifact on arm32, arm64, power5 and amd64 - compile to wasm once, run anywhere (nginx unit would still need to support your target).
Your runtime theoretically don't need is support - compile to wasm, run on FreeBSD/arm.
You can compile your c microservice to wasm, and your rust microservice, and your c++ microservice to wasm - and deploy them sandboxed via the same stack - reducing complexity (note that another option is to deploy via nginx unit - different way to reduce complexity).