Lukas s the best private messenger app in terms of technical achievements and potencial
It looks really good but:
How does it work? When the app is first started on an Android device, it starts the background service that keeps the TCP connections to the messaging servers open with almost no traffic (only doing periodic checks that connections still exist). It consumes only a few percents of battery per day, depending on how stable your internet connection is, and delivers message notifications as soon as messages arrive.
I think it is going to be the same, I will test Signal for a week or so and if it drains too much battery, I guess I will just use whatsapp. I can't really make my family to change messengers again. They only use Signal because of me. I can´t keep changing the messenger app and teaching them how it works again.
It is what it is, WhatsApp is widely use and there's nothing we can´t do.