I meant an open source client implementation coded in plain and simple C (nothing related to speed, here, but being able to compile it with a small compiler is paramount, namely not one of the Big Tech compilers, namely gcc or clang). The main reason is independence of the client from the Big Tech web engines (which are honestly and fairly technical "abominations", including their SDKs).
That said, for something discord like, the best small clients for interop would be an IRC bridges augmented with special and specific commands. There are many implementations of IRC clients and, what is very important, it is easy and reasonable to code an alternative (on top of a crypto lib ofc).
Or a plain and simple C client?