The dream for any kind of tool like this is to only have to define your data structures once, and use the tool to "generate" related code rather than try to keep two different artifacts in sync (e.g. a GraphQL schema and this DDL).
How far along that path has this project progressed? I can't really tell from the main page.
You might find something like Hasura interesting.
It is a GraphQL server that sits on top of your Postgres DB and the schema reflects the table schema. It's quite powerful right out of the box.
If you combine that on the front-end with Apollo and a Typescript types code generator, you end up with strong typing all the way from your database to the front-end.
has GUi tooling also.
https://github.com/dosco/graphjin
You give it the Postresql script and you will see the new GraphQL schema in he GUI, ready to test. This means that is only one change point ever - the sql.
It also supports subscriptions.
for CI you can just put the script into your git tree and it will pick them up at the start of a deploy update.