Answer
The correct long-term architecture is designing custom/configured projections more granularly from the start — breaking a broad projection into more narrowly-scoped ones, and grouping pages into logical page groups that match your actual access boundaries, so different user communities can be granted access at that finer level via permission sets rather than an all-or-nothing single projection. For pages you already have structured broadly, the practical workaround without redesigning the projection: create a separate Configuration Context, use Navigator Designer within that context to hide the specific nodes that shouldn't be visible, and assign that context to the users who need those nodes hidden — this achieves node-level visibility control without needing to restructure the underlying projection.