Thank you for the constructive answer.

I thought Signal was open source, and the distributed binaries matched the source, and that is was allowed to run your own servers. Are the servers even open source?

Are there lirerature regarding the technical/conceptional bits Element/Matrix? What is the tradeoff there?

Element is really slow on mobile, Signal and WA show my list of conversations in fewer than 5 seconds. Element needs ~10 seconds just to load UI, then 10 more seconds to sync list of active conversations, then I enter into a conversation and it needs between 2 seconds and 2 days to synchronize e2e keys. I can literally leave the conversation open, phone in charger for night and it still can't sync message. How do I explain to my parents that their message from 2 days ago "call me when you're free" didn't arrive because Element couldn't read it? They changed name 3 times already, changing APP ID, forcing me to reinstall it on all devices, update all my bookmarks in browser, having to sync all keys between all devices, not only on my devices, but also my family members who were using it. Their initial-setup of the app is really bad experience. Sometime I can NOT have two devices online at the same time to login and send message from new third device. It's cool on browser, I had nothing bad experience on mobile + web.

Signal is simply best because it works as SMS client AND encrypted messages client. Best UI/UX, one app to rule them all, consistent behaviour, not owned by FAAMG.

Thanks for your insights, I’ll definitely look into Element/Mattix. I didn’t know Signal was just another scheme to collect private data. But I always knew that WhatsApp == FB yet I couldn’t do much due to network effects. Decentralizing the web has never been so important as now.