It is still kind of around, but it became a completely different kind of a network under its new ownership. Most channels went to libera.chat, but others went elsewhere.
Not at all. Have a look at https://snikket.org for example. This let's you set up your own XMPP server that "just works" in a couple of minutes, and then you can hand out invites to your friends and family, so that they can install the Snikket app (Android or iOS) and are automatically registered and in your contacts in a few taps, without them even needing to know what XMPP is.
The server is the well-known Prosody, dockerized, the Android app is a re-skinned Conversations, the iOS client is based on Siskin IM.
And just like that you have a working, private, self-hosted, end-to-end encrypted cross-platform messaging system that also support a/v calls out of the box.
It really is pretty cool.
Imo they needed to be stricter about what constitutes a standard XMPP server, especially with security-related stuff. Look at how browsers managed to ban old TLS versions and discourage plain HTTP.
And less important but just annoying, XML was a mistake that they keep defending. Really only made sense for rich text message body, which nowadays nobody cares about either. I've seen a project where they just shoved JSON into it and called it a day.
I have also looked for VoIP providers offering competitive per minute rates to European phone numbers with no monthly fee. I did not find much. VoIP seems to be somewhat popular in Germany and there is no lack of providers. But their contracts include a German phone number which I don't need and cannot even legally get because I don't live there. I don't think SIP vs XMPP would matter for me.