A collage of 3 different screenshots taken from my phone. They depict, from left to right, Element (Matrix), Conversations (XMPP) and Signal, all displaying the ability to verify which devices actually have access to your account or messages.
https://files.mastodon.social/media_attachments/files/111/616/576/660/552/180/original/6d1c366ffd0169aa.png