Now I tried Debian as well. It boots fine, but the username & password mentioned are incorrect. There's some way to go until this thing is usable I would say.
Entire host macOS was crashed. Must be a bug with macOS. May be it is fixed by now, I don't really want to try as I don't like when my OS crashes. You can inspect qemu command line from UTM, I'm not sure if I saved my scripts, but there're some weird flags which I had no idea what they're for, but when I removed them, it was boom, reboot.