Answering my own question.
We ended up using an API management service (in this case Azure) to consume the initial OutSystems swagger and then enriching the operations and definitions in that platform.
Some of the customizations (not possible in OutSystems) we added were:
- Tags
- Summary
- Authentication
- Responses (OutSystems always sets the response as 200, doesn't show the 400 with the error structure)
- Examples
- Servers