https://www.washingtonpost.com/technology/2023/08/02/encryption-dead-cow-cult-apps-def-con/ A new competitor to Tapir has appeared (fairly similar ideal).
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https://cwtch.im If you didn't know, this idea of encrypted apps is the very same idea which the Canadian non-profit, Open Privacy, had with Cwtch (although, so far that is... mostly... just a chat app).
https://openprivacy.ca/discreet-log/40_july-2023/ They also appear to be here on the fediverse. See @cwtch