Cloudflare actually has built in iceberg support for R2 buckets. It's quite nice.
Combine that with their pipelines it's a simple http request to ingest, then just point duckdb to the iceberg enabled R2 bucket to analyze.
There's no egress data transfer fees, but you still pay for the GET request operations. Lots of little range requests can add up quick.
It is time like this that makes self-hosting a lot more attractive.
You have to store the data somehow anyway, and you have to retrieve some of it to service a query. If egress costs too much you could always change later to put the browser code on a server. Also it would presumably be possible to quantify the trade-off between processing the data client side and on the server.