We have a large timeseries database in Druid - say 300M records; Let's say we move this to Delta ; What are our options for querying this data using various rich filters, groupby conditions and perform slice and dice queries on this data from non spark JVM ? It seems Delta standalone is insufficient. Does Presto/Trino etc. help in this case?

Yea, there are Presto / Trino connectors.