I installed #Signal and #Conversations_im on a clean install of #GrapheneOS on my Pixel 4a and measured the battery impact. The results are shocking!
Both messengers had only one contact: my regular phone.
I used my regular phone to send messages to the Pixel 4a (which was not used for anything else over the course of the experiment).
I always sent the same message via Signal and #XMPP (mixing up which app went first). In total I sent ~32 messages in intervals of 10mins to a few hours.
@daniel While you're testing with GrapheneOS, maybe you could check if it keeps the connection open for longer when the phone is locked. Since a couple of months or so, I see 0 connections in the widget when unlocking my phone after a while, but then it reconnects quickly. However, the battery savings settings are the same as before and I don't know why it would disconnect otherwise.