Hello @Kim
Welcome to Q&A forum!
Thank you for your detailed information in this case. As I am also a Teams member and use this app for work every day, I deeply understand your concerns. This will help our user experience become a lot better and more convenient for modern busy life, making sure we don’t miss important messages.
However, after double-checking, I also need to confirm with you first that there’s no built-in “unified feed” for all missed items yet. And as forum moderators, we cannot directly influence the product; that will be handled by the Microsoft Product team.
In that case, we can only provide you with some "workarounds" to make things easier and "guide you on how to give feedback" to Microsoft via the Feedback channel.
Based on the requests you listed, I will provide instructions to help you check more conveniently during your work process (My instructions will apply to the Microsoft Teams app on desktop).
1/ Unread channel posts and replies:
You need to select both buttons: “Unread” + “Channels.”

"Unread" + "Chats

2/ Unread @mentions, reactions:

3/ Missed calls & Meetings


Besides, please make sure that you have double check all these settings:

Finally, I sincerely recommend you go to Feedback community to submit your feedback through Microsoft Idea Community -Ideas · Community. Our product team is in charge of the site, and they constantly check customer reviews and feedback, The higher votes, the more attention the related team will pay on.

After you submit your feedback, please share this link in this thread so that I and other users who also have the same expectations can vote to increase attention to your feedback.
I have prepared a feedback template that you can refer to or add to according to your own requirements:
"*Title: A single unified feed in Teams that shows all unread or missed items, with a filter/toggle option.
This feed should include:
- Unread channel posts and replies
- Unread @mentions, reactions, and replies
- Missed calls and meetings
- Unread private chats (DMs)
Goal: Avoid switching between Chats and Activity tabs to catch up."
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