We make TiDB, a MySQL compatible open source database built for scale. TiDB is a distributed scale-out database that you don't need to shard. It uses RAFT consensus for reliability and features online migrations. Our underlying distributed key-value layer, TiKV, is a CNCF project.
Our tech stack is Go, Rust, and Kubernetes.
You could work on our cloud hosted product or on the open source database itself depending on your skill set.