SMART data self test is greyed out in Disks?

From How can I check the SMART status of a SSD or HDD on current versions of Ubuntu 14.04 through 18.10?

SMART option greyed out

This can happen with NVMe SSD’s. You need to install NVMe SSD specific
SMART tools:

sudo apt install nvme-cli  

Then run the program to report health of drive:

$ sudo nvme smart-log /dev/nvme0  
Smart Log for NVME device:nvme0 namespace-id:ffffffff  
critical_warning                    : 0  
temperature                         : 40 C  
available_spare                     : 100%  
available_spare_threshold           : 10%  
percentage_used                     : 0%  
data_units_read                     : 28,167,888  
data_units_written                  : 19,397,424  
host_read_commands                  : 561,183,142  
host_write_commands                 : 171,788,833  
controller_busy_time                : 1,354  
power_cycles                        : 2,385  
power_on_hours                      : 1,363  
unsafe_shutdowns                    : 133  
media_errors                        : 0  
num_err_log_entries                 : 608  
Warning Temperature Time            : 0  
Critical Composite Temperature Time : 0  
Temperature Sensor 1                : 40 C  
Temperature Sensor 2                : 51 C  

The most important data point is:

percentage_used                     : 0%  

When it hits 100% it is time worry about replacing your drive. That
said this drive is two years old and still at 0%