AngelScript is not a transpiler. It's a runtime scripting language with an interpreter designed for easy script reloading at runtime, and I think there's even a JIT out there for it too. It's a valid competitor to Lua for the same use cases Lua serves. The only difference for integration may be that AngelScript is implemented in C++ and not C. Probably a C wrapper API could be (or has been) developed but that might not solve the problem of lacking a C++ compiler for your embedded platform.