These things should become plausible once the engine supports recursive CTEs and incremental view maintenance. In the meantime you could exploit Arrow interop with other engines (while keeping XTDB as the source of truth) - people have been building in this direction, e.g. using Polars in "Chrontext: Portable SPARQL queries over contextualised time series data in industrial settings" [0]

[0] https://www.sciencedirect.com/science/article/pii/S095741742...