Hope to see few changes/improvement after sony xz premium.
1.type c to be 3.1. So as to transfer files faster.
2. Wireless charging capabilities.
3. Digital audio Dac built in , to make a better listening to song. Sony have this technology, why can't they implement this in their phone. To be the leader in this.
So that everyone buy the phone just to listen to better song.
Thought the points you made, Sony already have them.
1) Type C to 3.1
You need the Sony UCB30 ($39.90 or so) for 3.1 speed.
https://www.sonymobile.com/sg/products/accessories/usb-type-c-cable-ucb30/
3rd party or after market one try not to get.
2)
Sony had wireless charging way back during Z2 era.
It didn't work out that good for Xperia that is why it stopped.
Since you need compatible case and the charger.
Samsung had this but to be honest, for charging best use USB cable
than such method.
3) Since Z2, Xperia phone slowly have DSHEE HX engine and etc.
build it into. Go under settings you should be able to see it.
Z2 doesn't have such better DAC but it still sound nice.
It also depend on your earpiece/headphone if you want better sound.
Out of box those earpiece won't do the job so try to invest something better.
A tip from me try to get earpiece/headphone that have in line mic cables.
Can listen to music as well as answer to call.
Unless you have budget get a Wireless headset.
I don't use Xperia for music listening but Walkman instead.
Dedicated music player the SQ is way better than any HP.
Take note big audiophile headphones especially with impedance higher than 24ohms.
You need a DAC to drive them properly as usually handphones can drive 24 ohms comfortably.