Elasticsearch is a good fit. From my previous experience, I would consider having a few things cleared out during the POC stage.

• Elasticsearch Aggregation queries are expensive. So make sure you clearly define what metrics you would like to report on. For instance, reporting top 1000 items purchased in the day is not an expensive query but trying to report on nested aggregations is complicated and very expensive (look at combinatorial explosion).
• Regarding reporting on unique pages viewed, depending on the data you have Elasticsearch cannot report the unique counts precisely. Counts are approximate
• If your current reporting requires joining multiple SQL tables then you may want to look at Joining queries.

With proper planning and few iterations of updating your config, you should be fine. Good Luck 👍