I would like to be able to use Data Layers and Actor Filters with standard (non World Partition) level streaming. The features seem at least conceptually compatible. Depending on a runtime consideration, I would like to be able to spawn a level instance with data layer A activated and data layer B hidden.
Have you considered using WP levels while deactivating the streaming? That would result in a single level being generated while allowing using Data Layers.
After further analysis, you can’t use Data Layers or Actor filters when spawning a LevelInstance at runtime. The Data Layers depends on the data being split on separate cells which is not the case for the Level being instanced. Actor Filters are applied in the editor when the cells are generated (Pre-cook\Pre-PIE).
This is likely a case for PCG or custom code that spawns the desired configuration of actors.