Seems this particular twitterer made the mistake of trying to implement their own GraphQL server from the ground up. Never do that! There are ready-made servers with neat resolver patterns which allow you to respond to queries with well defined entities while fetching their fields from any source.
That said, never do that, either! There are ready-made GraphQL adapters available for pretty much any database, and there are some very promising ”GraphQL-native” databases out there too!
And then there is Prisma, which is a one-stop shop for all your app’s GraphQL needs, whatever the database.