Migration tools split into data movers (Google, AWS and Azure DMS, pgloader) and schema change tools (Flyway, Liquibase, Atlas, Bytebase), and many projects need one of each.
Google DMS lists no added charge for native PostgreSQL or MySQL moves into Cloud SQL, and Bytebase is free up to 20 users and 10 instances, then $20 per user per month.
Liquibase Community moved to the Functional Source License in version 5.0, so check each tool's current license page before you standardize on it.