With guidance from Michael Dürig, I recently developed a way to expose Segment Node Store's internal information through the NodeState API.
The concept is similar in spirit to the proc file system in Linux: the proc subtree exposes internal information in a straightforward manner, enabling consumers to rely on a well-understood API to access the data. This proc subtree shelters tooling from variations of the internal APIs of the Segment Store. As long as the data exported through the proc subtree is stable, the same tools are going to work across different versions of the Segment Store with minimal to no modifications.
The proc subtree has been developed in this branch on GitHub. I created this issue in order to review the work done so far, and to track the contribution of the proc subtree in Oak.