Similar thoughts and after hopping a bit I’m liking Solus really well. It’s rolling release but what they call “curated” rolling release. They take a little bit of time to iron stuff out. There’s a weekly update cycle.
The installation is through live ISO and was pretty easy, took only a few minutes. They have a Plasma ISO too, since you mentioned wanting KDE.
As a plus, I’ve not once used the command prompt in the past couple of months since I installed (GNOME first and then since the last week, KDE). I’m not averse to commands but I do want something that I can recommend to my less techy anti-capitalist friends. My games have all been working fine too.
Edit to add: I think they’ve also mentioned that their aim is for a personal desktop.
You want to run it on the phone itself? I don’t think any phone would be good enough for that. The issue with AI assistants is not just privacy. It’s also the resource consumption (and of course stolen content). It’s so high and only these big companies with huge server farms can do it.
If you just want a voice assistant for simple commands, I’ve heard of an open source local assistant called Dicio. But I don’t think you can talk to it like ChatGPT or something.