Project health asks: am I hitting my milestones. Program health asks: are the milestones the right ones and is the trajectory sustainable. Those are different questions that require different data and produce different interventions.
A program where every project is green but the team is overloaded, the scope keeps expanding, and the stakeholders are misaligned on what success looks like is a program with unhealthy fundamentals dressed in green status. Project management tracks the projects. Program management tracks the health of the whole.
The indicators I watch at the program level are things that do not appear on a Gantt chart. Decision latency: how long does it take the program to make a decision after it needs one. Escalation rate: how many issues are surfacing above the program level that should be resolved within it. Team sentiment: are the people on this program energized or exhausted. Stakeholder alignment: do the people who need to agree on success still agree on it.
Those indicators are harder to quantify than milestone completion, which is why most reporting ignores them. But they are leading indicators. A program with rising decision latency and dropping team sentiment will miss its dates. A program that is two weeks behind schedule but has clear decisions, aligned stakeholders, and a team that understands the recovery plan is often in better shape than its status report suggests.
Report both layers. The project-level view tells you what is happening. The program-level view tells you what will happen next.