The libraries are embedded in quite a few places; for example it's used in every single Docker for Desktop instance:
- https://mirage.io/blog/2022-04-06.vpnkit
- https://www.youtube.com/watch?v=zqFDEDl5Zes
- https://github.com/moby/vpnkit
- https://speakerdeck.com/avsm/the-functional-innards-of-docke...
And then there are deployments in QubesOS, Xen, Nitrokey, etc. Bear in mind that MirageOS is a library OS, which doesn't just mean "compile to a standalone kernel instance". It just means that it can be linked into all sorts of embedded environments, some of which are the solo5 or Xen backends you see in talks.
More on the Mirage blog: https://mirage.io/blog