Most of the users I've seen using Nhost (and Hasura) treat data/the db as the source. Given that you have raw access to postgres, you are also the full owner of your data and you can swap interfaces as you see fit (I've seen users use Hasura internally and not expose it to the internet)

Notice, also, that Hasura has support for REST endpoints.

If you don’t care for object-level caching, you can always query a GraphQL endpont with just a simple HTTP client.