I used to feel the same way, but the interface is actually super customizable if you are ok with editing config files!

Here is the manual.

There is also a huge variety of third party scripts, like this one shows thumbnail previews when hovering over the seek bar.

Yes

Relevant Silicon Valley scene

Signal is certainly not. It’s open source, and verifiably end-to-end encrypted. The only information that they have about you is your phone number, when your account was created, and when you last connected to the service.

Telegram is not so privacy friendly, with a major problem being that it’s not end-to-end encrypted by default.