Zero Trust has been with us for the best part of a decade - since the likes of the Jericho Forum, Google's Beyond Corp and ex-Forrester analyst John Kindervag have all promoted a view of moving the concept of "trust" from a location to a concept based on the identity, device and associated context.
Version 2.0 of the US Department of Defence Zero Trust Reference Architecture has been cleared for public release and is a good, detailed read regarding an actual migration and implementation model. The document is available here.