https://www.securemessagingapps.com/ if you see closely for session , it says that attachments are centralized in their servers in canada
session tries to promote their oxen cryptocurrency and lokinet which imo crypto currency are used by baiters to bait people into ruining their money
you dont understand what signal /molly is , do you ? they are centralized server and OP specificially asked not centralized server / server for that matter
matrix is good but it still need server , plus matrix.org takes quite a bit of metadata
jami’s good but it uses turn server to verify your name
briar’s bluetooth functionality can be violated plus no good ui/ux
just search seytonic bluetooth on yt , you can find it preety easily ngl