[wwright]

OCI in general doesn't need to have very much overhead at all; it's just a few syscalls after fork() and before exec() (that trivializes it a bit, of course). I wouldn't be surprised if native runtimes already do some of the same work; it's just good practice when designing mixed-trust systems on Linux.

Docker's specific implementation may offer other hurdles, of course, but AWS Lambda could easily use one of the many other implementations of OCI.