Mail clients have run into the same issue several years ago and still doggedly try to make "unified inbox" happen.
The operating system deprioritized apps with their own feeds, and instead provided a number of "hubs" that were like topical inboxes that collected data from multiple APIs.
There was a People hub that showed your contacts aggregated across phone contact book, Windows Live, Facebook, Gmail, Twitter... Notifications about people you know would show up in this screen regardless of the service. And there was a Photos hub that similarly showed photos from everywhere: local, Facebook, etc.
It was a truly original idea for a social media oriented phone. But companies like Facebook and Twitter were not too happy about the idea of being API pipes with little or no control over the user interface on the user's phone. Of course they had some good reasons not to trust Microsoft on this, given Microsoft's past behavior. I think FB shut down the necessary APIs completely a few years later and replaced them with more limited options.
The unified timeline is the whole point. However, for me, this app gets two things wrong:
1) I'd also want IM feeds on the same timeline. Like, Messenger, Teams, WhatsApp, etc. I know it's probably impossible due to how obstructionist and anti-user the chat vendors are, but I keep dreaming about it. Most chat conversations are, in my mind, in the same general category as HN links or incoming e-mail: "thing that I need to pay a minute of attention up front, and then possibly 15+ minutes dealing with".
2) It's iOS only.
It aggregated RSS, Twitter, Digg, Facebook, Flickr, Reddit.
So it’s a very old idea that’s just coming back - like a lot of things, it goes in cycles.
We ended up selling the software to another company. My personal advice - never build your business on top of other companies data/APIs, they can cut you off at any point.
Chats: yes. Because each separate chat is a separate room, and ultimately, for a personal use, there are not that many of them.
Feeds from social media though? A hard pass. Especially now, when so many people cross-post the same content to multiple networks.
Feels like a solvable problem. Do a string comparison and then just put multiple icons next to the post.
Still feels like a solvable problem that improves the experience in my book.