I'm not super familiar with this, but it seems like the question is what is "full-system" in this case if each application is sandboxed with its own embedded kernel? I mean there's no shell, ostensibly all other applications and system functions are bundled similarly, right?
It'd make exploits more difficult, but you'd still be able to upload your own code to do whatever you want.
The trouble is that instead of uploading "/bin/sh" you'd have to upload the whole shell which you'd want to run; instead of making a syscall for something that a normal kernel would do but this one doesn't, you'd have to compile and upload appropriate code (including device drivers) to get that done.
