I’m unsure about GBQ specifically, however for getting Airtable data into the Google ecosystem, we use the Railsware Airtable Importer which syncs data periodically over to GSheets. It’s worked flawlessly for us for over a year now, it’s extremely simple and robust. For you, it could cut out the first export step of your process and keep data synced.
Skyvia offers a cloud data integration platform that allows for easy connection between BigQuery and Airtable without the need for coding. This platform operates on a freemium model, providing users with a range of features at no initial cost.