> When I tried Signal, I saw an empty list and had to add numbers / find people myself That's not how it works; Signal directly gives you the list of contacts

> When I tried Signal, I saw an empty list and had to add numbers / find people myself That's not how it works; Signal directly gives you the list of contacts that are available, just like Whatsapp or Telegram. The most likely is that you had an empty list because no-one in your contacts have it.