I met one guy who had a FAA Flight Navigator ticket. Wasn't even that old of a guy (at the time). The hoops he had to jump through was impressive, and even then he got some lucky breaks to make it happen that would be improbable to duplicate.
You can still download the FAA's Navigator book:
https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-18.pdf
Engineer tickets are going the same way, but plenty of operators still require FEs. Not sure what's gained in going out an getting your ticket other than to say you have it. In any event, the FE ticket sure seems FAR easier to actually do than the Navigator ticket. That math stuff looks complicated.
I also think there is a wrinkle with the FE ticket in that you need an actual airplane at some point, and not just do it all in a sim. When I did mine, you had a restriction on the ticket until you finished OE, and you had to take your OE form and ticket to the CMO to get a unrestricted FE ticket.
Richman