There are also unofficial IodéOS builds for newer Sony Devices
and for other Sony devices in the same 'family ’ as XZ1 Compact
All in addition to the Sony devices officially supported by IodéOS
Xperia XA2 (pioneer)
Xperia XZ1 (poplar)
Xperia XZ2 (akari)
Xperia XZ3 (akatsuki)
Sony make great devices and, via their Sony Open Devices program, they actively support the Android Custom ROM community (unlike many other manufacturers, who make life as hard as possible for custom ROM developers and maintainers). And VoLTE should work on most (all?) of them I believe, so long as it is supported by your network provider
PS The unofficial IodéOS builds are now all available from the LineageOS for microG download server at https://download.lineage.microg.org/IodeOS/