There's also a JavaScript unikernel project: http://runtimejs.org/

Notably, there's ongoing work (with an already functional result) to run Mirage on top of the low-level drivers provided by Rumprun. The idea in doing that is enabling the "top-level" Mirage stack to run in environments for which they don't have native OCaml drivers yet. (disclaimer: I don't speak for Mirage, though I do speak for Rumprun)

>OSv applications run in a JVM

While this may be the most typical use for OSv, my understanding from their wiki[0] is that OSv can handle Ruby or Node, or Linux apps (most of the Linux ABI is supported).

[0]https://github.com/cloudius-systems/osv/wiki