Hmm - okay some quick thoughts:
• The bronze, silver, gold is about a data quality framework in which at each stage, the data at the next level is cleaner than the previous.
• The concept of a medallion architecture would be orthogonal to the development lifecycle whether it would be TDD, agile, or any other development lifecycle.
• The lakehouse itself is related to the medallion architecture in that we use the medallion architecture to keep the lakehouse clean. BUT, you could employ the medallion data quality framework on a data lake, data warehouse, document store, etc.
• Instead, the lakehouse is about taking the best of the database/data warehouse (simplicity, easier manageability, transactional consistency) and data lakes (scalability and flexibility)
• The Lakehouse absolutely should be setup with SSOT in mind but there are many valid exceptions to that generality.
• In terms of entities and use cases, this is apropos to the context of data marts where we built databases from datawarehouses that were use case, business domain (or entity) specific.
• You can do the equivalent with lakehouses as well - i.e. build "lakeroooms" or "lakemarts" for your specific entities or use cases.