Have built something similar by forking the Datadog tracing library to also send each Span as a JSON to Kinesis Firehose, and then to S3. From there you can easily query it using AWS Glue (for schema inference) + Athena (as the actual SQL engine).
It's indeed really nice for digging deep or doing performance analysis, though I'd say for 99% of cases, the Datadog APM UI + query editor is much preferred. In practice, we'd occasionally see that we can't express a query in the DD UI and run it through SQL, but it happens very rarely. It's also nice for cheaply achieving 100% sampling if you ever have the need to find a single specific request that's happenned.
I wonder what the UX would be of using something like this with a tool like Metabase for the UI (with an actually fast query engine underneath, like Timescale or ClickHouse).