Maybe the OP is thinking of reading/writing to DuckDB native format files. Those require filesystem semantics for writing. Unfortunately, even NFS or SMB are no

Maybe the OP is thinking of reading/writing to DuckDB native format files. Those require filesystem semantics for writing. Unfortunately, even NFS or SMB are not sufficiently FS-like for DuckDB. Parquet is static append only, so DuckDB has no problems with those living on S3.