Hopefully they're still working on getting it rated. I emailed them last week and received this in response:
Originally Posted by Essential Support
Thanks for writing in. Questions about the water and dust resistance qualities of the Essential Phone are being asked by lots of people. It's a completely fair question and we hear you. Right now I don't have an official response to give you, but I encourage you to stay tuned to
Essential.com and our social channels for updates and announcements.
Judging by the ambiguous response, it's possible they're still testing and will add a rating to it later or it won't get rated at all.