I had a need to develop various types of Airtable to Google Cloud Firestore syncs. Still need to create more types and fix some issues, but I figured I'd share what I have so far with the community. It's easy to use and works just as advertised for me.

https://github.com/antquinonez/Airtable-Firestore-Sync

• FULL_REFRESH: Deletes all existing data in the Firestore collection and replaces it with the current Airtable data.
• REPLACE: For each record in Airtable, deletes any existing records with the same primary key in Firestore and inserts the new record.
• UPSERT_CHECKSUM: Compares each Airtable record with existing Firestore records using a checksum. Updates Firestore if there are changes, or inserts if the record is new.
• UPSERT_CHECKSUM_WITH_DELETE: Similar to UPSERT_CHECKSUM, but also deletes Firestore records that no longer exist in Airtable.
• VERSIONED: Creates a new version of each record in Firestore, marking the previous version as not latest
• VERSIONED_SET: Creates a new set of all records if any changes are detected, using a version ID. Marks all previous records as not latest.