Nice overview of pg-osc. I'd like to also mention pgroll, which has some similarities, but does this at column level rather than table level and takes things further: it can expose the old and new schema simultaneously (using views), which means you don't need to maintain backwards compatibility code in your app.
Plug bomb, but pgroll looks pretty good. I do a lot of copy/renames to update fields on very large tables with a lot of indexes, if it could automate those scripts including dependencies I would use it for big bespoke migrations in a heartbeat.
On the smaller side, I can see this being useful to avoid migration bugs, but being its own migration tool isn't a great choice since ecosystem specific migration tools have a lot of useful options and can be used programmatically. I'd make a pgroll plugin for alembic and other common ecosystem specific feature-rich migration tools that hooks into the ddl emission to transform a "dumb" migration into your juiced up migrations. That'd make it an instant use for me.
Disclaimer: I work at Xata, we maintain pgroll.