Comment by cpuguy83

Yes buildkit can do this. You can also use buildkit to create a bootable VM, just that nobody is doing it. You can use estargz to fetch just the pieces you need from a dependency rather than the entire depdency as well. Really all of the things you mentioned should be possible with buildkit, just that the focus of most things is Dockerfile which has much more limited functionality (though some of the things mentioned above still apply to Dockerfile).