All things being equal.....that SSD is bad. The SSDs in the MacBook Pro 13" 2016 & 2017 non-touchbar laptops have an extremely high rate of failure which normally is encountered when powering on the laptop or waking it from sleep because the SSD is unable to go ready soon enough to communicate with the system.
Or maybe the Logic Board in your laptop is bad or damaged. My money is on the SSD being bad.
Unfortunately the only way to confirm the SSD is bad is by testing the SSD in another laptop....or possibly by placing the SSD into an external OWC enclosure to see if the SSD disappears when connected externally (put it to sleep for five minutes & wake it up to see whether the SSD disappeared again (depending on how bad the failure is, you may need to do this multiple times before you find the SSD missing).
I highly doubt that DriveDx will show any health issues with the SSD for this particular problem since this is generally an issue with the SSD's controller which has no health monitoring.
FYI, I don't recommend spending any money on any Intel USB-C Macs for multiple reasons. Plus this specific model laptop has many other known hardware issues and a couple of lesser known issues. The money spent to fix this laptop is much better put towards an M-series Mac or some other laptop.