We have several C# applications using a shared monolithic database (on-premise SQL server) using Stored Procedures as an exclusive interface.
The C# code repositories include only Stored Procedures that are relevant to them, which means a single database is split into multiple repositories.

We are currently using a shared DEV environment restored from production (after some modification to sensitive data, etc.)

I want to move to our version control being a single source of truth and put the whole database into one repository so I can generate empty DB for each developer (that would allow me to unit test, etc.)

But that would create problems for developers: they would have to keep a branch of their app and branch of a database in sync and coordinate extensively.

How to solve this without moving the apps back into monolith as well?