Is there any public S3 bucket with event data we can use for testing / demo
I’m not aware of anything like this available.
If you want to understand what the data looks like the Snowplow collects, you might find this page interesting: https://snowplowanalytics.com/explore-snowplow-data-part-1/
Other than that, you could set up a Snowplow Mini and track some events into the internal ElasticSearch, or your could follow our Open Source set up guides to spin up a collector, enrich & S3 loader which will load enriched data into S3.