I'm learning about consensus and I'd like to explore SCP in depth. However, the stellar-core implementation is difficult for a newcomer to grok. Is there a minimal SCP implementation elsewhere I can learn from, ideally in Rust or another high-level language?
I believe there are implementations either complete or in progress, but am not sure if any have been publicly released. If you want to implement SCP, I strongly recommend starting with the protocol specification draft rather than the whitepaper. Many of the people following the draft hang out on the IRTF Decentralized Internet Infrastructure list, so that would be a good place to hear about or discuss implementations as well as to provide any feedback might have on the draft.
I am not aware of an alternate implementation of the SCP code. I’d recommend using the white paper as a starting point to take advantage of whatever language you’d pick to do it.