Not even Telegram supports multi-device sync for 'locked' chats. So if you really care about security, multi-device sync is not a feature, it's a bug anyway. I

Not even Telegram supports multi-device sync for 'locked' chats. So if you really care about security, multi-device sync is not a feature, it's a bug anyway. I know only 1 guy who uses Signal and he is an AT&T systems administrator and linux addict. He understands the difference. The rest, use either iMessage or Telegram and don't really care about the rest.