It seems that the formerly announced PlayStation Discord integration is coming very soon, as proof of it has been spotted on the actual Discord backend itself. In addition to this, a Discord user has spotted the icon itself now in the integration options, which points to its release in the near future.
As first reported by a user on Reddit, a Discord icon now appears in the integration bar alongside others like Battle.net, Facebook, Reddit, Spotify, Steam, Twitch, Twitter, Xbox, and YouTube. Check out the thread and the screenshot below.
You will soon be able to connect your Playstation Network account to your Discord profile! from discordapp
Additional evidence of this comes from a comment in another thread, as the user states:
Discord being an Electron/web app also makes it trivially easy to datamine, and someone has a GitHub repo setup to track changes made to the JavaScript files in the client. https://github.com/Discord-Datamining/Discord-Datamining
Here’s the specific commit in the repo that includes the PlayStation account link feature: https://github.com/Discord-Datamining/Discord-Datamining/commit/a73a76ede1c6d19c82fdf4caf78aa0dd8bfa10ac
There you have it. It appears that PlayStation players will soon be able to utilize Discord directly for communicating with their group or party members thanks to this direct integration. While we know this integeration is incoming, Sony has not disclosed any time frame for this, but given this backend change, we’re hoping an announcement is incoming soon.
Update: Our contributor AJ (Twitter link) has also added the following findings:
Sony has been quiet ever since announcing their partnership with Discord in May of 2020, when they shared plans to “bring the Discord and PlayStation experiences closer together” starting in early 2022. With the New Year behind us, it looks like they’ve made some progress on this front.
A now locked Reddit thread posted on December 16th, 2021 shares a screenshot of the “Connections” section of the Discord app, now with a a Playstation Network icon available. Discord has various other apps it can connect to, such as Steam and Spotify, in order to do things like share activity on your Discord profile, or invite friends to games directly through the app.
Unfortunately, the Playstation icon doesn’t appear to be in the final Discord client yet. Later on, the user shares that this screenshot came as a result of unused files found in the beta version of Discord. Regardless, this shows that the option to link your Discord and Playstation accounts could be on the way sooner than we think.
Speaking to someone with knowledge of the subject, it appears that the Playstation Network is indeed mentioned in the beta Discord client, right alongside Twitch and Steam.
Further digging confirms that you’ll be able to display PlayStation games you’re playing on your Discord status. 
This ability to display play activity on your Discord profile was an expected one, however. Xbox has had a similar option since 2018. What Playstation players really seem to want to know is, will they be able to communicate with their PC and mobile friends directly through their console?
We’ll have to wait for official news from Sony on that front. It appears the ability to connect via the internet is blocked to the public right now, so there’s no way to tell if this feature is coming. We were unable to find any mentions of it in code.
That certainly doesn’t mean it’s not coming. From the sounds of it, Sony plans to make this a robust feature, and specifically mention the ability to “communicate more easily while playing games together.” It looks like that option could be on the way soon.