Is it just me, or isn't "BareMetal OS" an oxymoron? I guess it sounds cool, but taking an established term and use it as a name for the exactly opposite seems confusing to me. Please be responsible when choosing names for your projects :)
Exokernels don't, actually, abstract over hardware. They merely manage resource allocation.[1] So, "BareMetal", is not such an oxymoron, provided you're talking about the kernel itself.