Some objects are black

Hello. Last month i was creating a game for pc. Now i decided to make it for android. When i turned on Android Viewport, some objects became black. I know it is because of no directional light but I need a night. How can i fix black objects without directional light?

some ideas:

make them unlit.

have an ambient light.

use a fake directional light material. there is a post for that in the forums.