I think this requires support from Piefed API which doesn't exist right now.
Summit
Community to discuss Summit, an open-source Lemmy reader for Android.
App (Play Store): https://play.google.com/store/apps/details?id=com.idunnololz.summit
APK: https://github.com/idunnololz/summit-for-lemmy/releases
Source: https://github.com/idunnololz/summit
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Website: https://summit.idunnololz.com/
Please take a look at this post https://piefed.social/post/1088682
I thought about this a bit more. The issue with multi-communities is that because they are client sided, they can put a lot of load on the server and they are much slower the more communities there are. I can definitely combine the two features into one but I don't have high hopes it will actually work well. There is also a limit on the number of communities in a multi-community at the moment and some of the topics defintely go over that limit.
I will need to think about this more but I think I can commit to at least having some way to view topics/feeds in the app to start.
Thank you for taking time looking into this. Appreciate the effort going into making this the best Lemmy/Piefed app.