Dolt is Git for Data: a SQL database that you can fork, clone, branch, merge

If this could somehow work with existing production MariaDB/PostgreSQL databases, this would be the next Docker. Sad that it requires its own proprietary DB (SQL compatible though it may be, it's not my existing database).

I wish something completely free like this existed just to manage database migrations. I don't think anything is quite this powerful/user-friendly (if you can call Git that) and free.

Are you familiar with SQLAlchemy Alembic[1]?

For best results it requires modeling your project in Python using SQLAlchemy, and even then, some migrations may require manual tweaks. But it is free and supports an extensive range of database systems.

[1] - https://alembic.sqlalchemy.org/en/latest/