I think just showing links to nostr posts as embeds like twitter or youtube would be enough "integration" from SN side.
I think what SN is really missing is a public (authenticated) API.
Then stuff like this can be built on top of it instead of messing with the code of SN like this:
Just move the entire Stacker News content to a custom Nostr relay, make the default client talk primarily to that relay -- but configurable.
nostr is cool but I don't think it's a good idea to entangle different applications.
With a public API, one should be able to write a bot and send every post or comment on SN automatically to a nostr relay.