According to the "Loading Signed Exchanges":
https://wicg.github.io/webpackage/loading.html#overview

```
A Service Worker for https://distributor.example.org/ gets to handle the original request. A Service Worker for https://publisher.example.org/ can then handle the redirect. If it needs to know that signed exchange content is available for the request it’s handling, it has two options:

1. If navigationPreload is enabled, the signed response will be available in the FetchEvent's preloadResponse. Note that this will also cause a network request for requests that aren’t served from a signed exchange.

2. clone() the request and set its cache to "only-if-cached", to retrieve the matching response from either the signed exchange or the HTTP cache. Note that fetch()ing a new Request with the same url will not retrieve the response from the signed exchange.
```

We need to explore how to implement this.