Actually, thinking about things that you could do, if your levels are curated and not procedurally generated you could position a shadow volume where your buildings cast shadows and have that volume trigger an event for any actor on entering/exiting to darken/lighten their material as if receiving shadows, it could even fade based on how much of them is inside the volume. You could also potentially mask this somehow based on which bits are inside and out so it looks like the shadow is cast but it’s really just a neat cheat. No idea how expensive any of that is on mobile though without doing in depth tests.
But you could use that to have the buildings cast shadows on movable actors such as turrets etc. but still have them as static and baking lighting. If light channels work on mobile you could then have a light for static and a light for dynamic then tone the modulated shadows on the movable channel down so it blends a little nicer.