Following the PS4 NMount Payload guide, PlayStation 4 developer @oneman123 shared news on Twitter that he has successfully mounted the whole PS4 Root as drive 'P' with Target Manager (instead of FTP) via 1.76 DevKit / TestKit. 
Offsets for PlayStation 4 developers:
Below are some related Tweets as well, and a tutorial from notzecoxao with help from VVildCard777:
Here's How to Setup PSFS Drive as root (/) instead of /data/ Tutorial from zecoxao, to quote:
First of all, a note. this is for testkit and devkit consoles ONLY! We are working on a way to bring debug functionality to retail consoles, but it might take a while.
These are the patches:
Due to the nature of devkits, only hitodama's payloads work on them, so i'll provide one payload for CTurt (for testkit) and one for hito (for devkit)
Testkit payload follows the CTurt procedure. Devkit payload follows the Hitodama procedure.
Good luck! If you do not feel confident on trying the payloads, just implement those patches yourself in your own custom payload
PS: Even though it's in the tags, credits to zil0g80 and wildcard for the sauces and patches
Offsets for PlayStation 4 developers:
Code:
*(uint16_t *)0xFFFFFFFF825FCFE6 = 0x9090; //devkit
*(uint16_t *)0xFFFFFFFF825FD001 = 0x9090; //devkit
*(uint16_t *)0xFFFFFFFF82607E56 = 0x9090; //testkit
*(uint16_t *)0xFFFFFFFF82607E71 = 0x9090; //testkit

First of all, a note. this is for testkit and devkit consoles ONLY! We are working on a way to bring debug functionality to retail consoles, but it might take a while.
These are the patches:
Code:
*(uint16_t *)0xFFFFFFFF82607E56 = 0x9090; //retail - testkit (doesn't work on retail yet, but offsets are the same)
*(uint16_t *)0xFFFFFFFF82607E71 = 0x9090; //retail - testkit (doesn't work on retail yet, but offsets are the same)
*(uint16_t *)0xFFFFFFFF825FCFE6 = 0x9090; //devkit
*(uint16_t *)0xFFFFFFFF825FD001 = 0x9090; //devkit
- Testkit payload: payload.bin (1.00 MB)
- Devkit payload: payload.elf (5.08 KB)
Testkit payload follows the CTurt procedure. Devkit payload follows the Hitodama procedure.
Good luck! If you do not feel confident on trying the payloads, just implement those patches yourself in your own custom payload
PS: Even though it's in the tags, credits to zil0g80 and wildcard for the sauces and patches