Regarding the Sony Xperia X Compact and custom ROMs…
If you are going to use any Android custom ROM based be aware that all the custom ROMs for X Compact (except some old, unmaintained CyaonogenMod 13/14.1 and LineageOS 14.1 builds for which the source code has been removed from GitHub and some stock ROM based ROMs) are based on Sony AOSP which for like two years or so contains a bug where on random basis (mostly on high GPU load) the phone restarts itself or "bricks" to the state a key combo reset is needed. I have struggled with these for like a year and abandoned this device for this reason, therefore I would not recommend this device for using it with any Android based custom ROM.

For clarification, I would not blame open source code as it is often maintained in developers' free time and I appreciate their work and will to do it but this bug seems to be in closed source drivers worked on mostly (except for providing logs) by Sony and that's why I personally feel rather disappointed.