This is definitely the way to go, especially with the more recent trend of embedding UI elements in world space, and VR/AR essentially requiring it.
Internal tools tend to be IMGUI, Winforms, or WPF from what I've seen. Essentially whatever the original author is most productive in. No need to be super performant because your only users are other devs with really high end systems and rarely an actual need for a constant 30/60fps.
Your engine likely already has a graph structure, event system, and input handling. The core pieces of a retained mode UI system are already there.
Internal tools tend to be IMGUI, Winforms, or WPF from what I've seen. Essentially whatever the original author is most productive in. No need to be super performant because your only users are other devs with really high end systems and rarely an actual need for a constant 30/60fps.
Your engine likely already has a graph structure, event system, and input handling. The core pieces of a retained mode UI system are already there.