This sounds a lot like Apache Ignite 2.x, though it does not have SQLite's level of polish.

It's never going to be embeddable, no?

It is a set of Java dependencies so a full data-bearing Ignite node will happily be an in-process part of your Java monolithic app or microservice. It has likewise bindings for .Net and some other languages but not so seamless as in case of JVM.