The default matrix.org servers are federated.
In terms of what the default Element install presents to the user upon launch in its GUI, I think it does offer the 'official' matrix.org servers as a place to create an account and sign in, start browsing 'rooms'.
https://www.vice.com/en/article/n7vq4k/thousands-of-users-un...
IOW, even though they say they don't want to control your conversation, they do want you in their hands.
Can you run it? Sure. Should you?
Please excuse me for being direct, I do not accept your defeatist attitude on this one. You won’t have stickers, such a shame, but you would have the ability to create your own signal service
But it doesn't. There are options. If I had to choose, I would rather invest this time and money to collaborate on the existing protocols that do have the goal of being fully open. Matrix and XMPP can do the things that I want and there are plenty of people working on them to overcome the present issues and challenges for mass adoption.
Why should I swim upstream by myself if there is no special reward for this kind of effort?
I know you are a nerd but your users are not.
However, my mother does use Element to talk with me and it wasn't that hard to help her download an app, tell her where to put the username and what is the name of the matrix server and quickly she was on her way to start a call and setup a room with the rest of the family where I share the pictures of her grandkids.
My users may not be nerds, but they are not stupid. They can learn.
Like nearly everything, "secure" is a spectrum and not binary. On that spectrum, Signal is overwhelmingly more secure than most messenger apps people actually use.
To me, Ricochet is the most secure instant messaging app for desktop. It would be even better were it to use Onion v3, and if it were available on Android, but then again, I do not really consider my phone secure by default with all the Google crapware. I disabled the default Google keyboard and downloaded one that does not require Internet connection and that is not related to Google in any way. It is so silly that I cannot even delete any apps that came with my phone. So they say its storage capacity is 32 GB. Half of that is spent on crap that came with the phone, splendid. In any case, I am going off-topic here so... :)