You will, though, end up fighting the system in some ways. CI/CD systems, unit test frameworks, configuration data approaches, etc, aren't equipped to (easily)

You will, though, end up fighting the system in some ways. CI/CD systems, unit test frameworks, configuration data approaches, etc, aren't equipped to (easily) spin up databases and connect to them. At least not in the more rapid cycle early end of development, versus slower cycling integration tests.