I come more from a JVM world. But aren't there any DB migration/refactoring tools in Rails to allow for changes to propagate across tenants ? E.g for the JVM,

I come more from a JVM world. But aren't there any DB migration/refactoring tools in Rails to allow for changes to propagate across tenants ? E.g for the JVM, there's Liquibase and Flyway, and I agree with you, setting that up took a good part of a couple of weeks of dedicated effort.