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Xmpp client
(lemmy.zip)
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
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Have a look at this one
Conversations (Encrypted, easy-to-use XMPP instant messenger for your mobile device) https://f-droid.org/packages/eu.siacs.conversations/
Yes, and it also consumes in stand by