What do you mean by "explicitly"? DocumentGroup sets up the undo management behind the scenes, implicitly.

I should clarify that the observation tracking(currently in beta) is a one time event, i.e. it is not sustainable or persistent, when used without @State and in a non-SwiftUI-context. Once the observation tracking has been evaluated, and the onChange closure is called, the observation will end, and you need to set up an observation anew. This may be subject to change for the release or post-release.