Consider the notes here as a work in progress... Things are in flux. Things break.
The manufacturer recommends you do not use the cable provided with your phone for anything other than charging. Instead, use a quality USB cable.
The Essential PH-1 does not have a headphone jack so in my car I use this bluetooth adapter to plug into my audio system.
I use these bluetooth headphones.
I also recommend this OTG adapter for connecting USB devices to your phone.
The most frustrating part of USB audio (on any device) is the volume steps where one it too quiet and another is too loud. However, on Android it is possible to give yourself two separate audio controls (one for the phone and one for the headphones).Settings - Developer options - Disable absolute volume
The need for root is reduced if one uses Firefox with the ublock origin plugin and Netguard. If you are considering root only for adblocking and firewall you might want to check those as a solution first.
Obtaining root for the first time is different from retaining it.
For stock Android 8.1 I recommend using Magisk for root.
Obtaining root for the first time
Retaining root after updates
Building and installing LineageOS
Life without Google apps
Google's camera software works with the PH-1.