I'm not using Session much, among the smaller messengers, most of my friends prefer SimpleX, although Signal and Matrix are still winning by a wide margin.

I did a comparison of the messengers: https://juraj.bednar.io/en/blog-en/2022/05/03/encrypted-messengers-comparison/ 

 "A few positive things about Signal. The applications are open-source"

It is not true!

You cannot reproduce Signal build. 

 https://molly.im/