> so basically, two sources of truth.

As I understood you don't, as SQLModel inherits from sqlalchemy ORM base classes. From the user guide, this is an example how to define the model and generate the table.

  class Hero(SQLModel, table=True):
      id: Optional[int] = Field(default=None, primary_key=True)
      name: str
      secret_name: str
      age: Optional[int] = None

  engine = create_engine(sqlite_url, echo=True)

  SQLModel.metadata.create_all(engine)