Kind of scary how easily and without resistance a militaristic new tech terminology, like the "Forward Deployed Engineer" (FDE), enters the common industry vernacular.

This is not a new role. On-site developers have been a thing ever since software has been on any site. Sometimes it's just nice to have someone there to be with the client and fix issues right away (and also bill all the hours for them being there). I've done this back in 2010. We called this "auf Baustelle sein" (German company)