This demo shows how Unity's LWRP or URP template works with shadowmask lighting mode. Currently, we can support at most 4 baked-shadow lights. As the following image shows.
The shadow information is baked in the shadowmask image. Even the workshop sets on the floor are removed, we can still see the visibility to the directional lights as well as the other two colored point lights.
For clarity, if you want to integrate these changes into URP, you can also see this branch which has the main code difference.