Just to clarify, Milvus is much more than a wrapper around FAISS. Our vector search component called Knowhere (https://github.com/milvus-io/knowhere) utilizes FAISS and Annoy and will soon include ScaNN, DiskANN, and in-house vector indexes as well. Milvus uses Knowhere as the compute engine, and implements a variety of database functions such as horizontal scaling, caching, replication, failover, and object storage on top of Knowhere. If you're interested, I recommend checking out our architecture page (https://milvus.io/docs/architecture_overview.md).

[EDIT]: Forgot to mention - Milvus development began in 2018 was open sourced in 2019.