Can a Service Worker update itself offline?

Question

Let's say that I have a service worker that, among other things, helps make a page or application available offline.

Now, the device which runs this application will be offline for a very long time. So long, in fact, that (obviously cryptographically signed and verified) updates via sneakernet might even be warranted.

Now, updating the page's content is pretty straightforward— but what about the service worker? Is there any way for it to update itself without a live, genuine HTTP server serving up a fresh Response?

For example, if I have installed the worker originally with {updateViaCache: 'all'}, does the service worker itself have any ability to affect the specific cache that updateViaCache uses—in essence to "trick" the browser into thinking an update exists?