It looks neat but, no Java SDK? Every company I've personally worked at is deeply reliant on Spring or the vanilla clients to produce/consume to Kafka 90% of the time. This kind of precludes even a casual PoC.
(S2 Team member) As we move forward, a Java/Kotlin and a Python SDK are on our list. There is a Rust sdk and a CLI available (https://s2.dev/docs/quickstart) . Rust felt as a good starting point for us as our core service is also written in it.
Merely as a "for your consideration," writing an SDK in a very, very different language can surface "rust-isms" in the way your API works that might not be obvious when using a homogeneous tech stack
I think of that as the "Chinese wall" of shipping SDKs: can someone not familiar with your product use it effectively from a language you don't know