Signal is shit, its a honeypot. It requires your Phone Number and that the persons chatting have each other in their contacts on device, even if you convince friends not to use WhatsApp, WhatsApp, Google, Apple and every other App, someone installed that can access your contacts knows your Name, Phone Number and People you are connected to.
Signal relies on NSA Cloud Servers and "security" features of Intel Processore that are going to be broken or probably there already is a backdoor.
You can't have it on multiple devices with multiple accounts, its a closed ecosystem and doesn't have a big community involved with checking the code. They get funded by US Gov. and tried to put obvious backdoors in their desktop apps.
Use Matrix.org , I also heard good things about SimpleX.
What do you use for scanning?