Hi, post author and founder of InfluxDB here. We're supporting Flux (our scripting and query language), InfluxQL (our original SQL like language), and SQL (specifically the Postgres dialect as that's what DataFusion supports). The query engine is DataFusion, which is part of the Apache Arrow project. We contribute to it significantly. So that's what's built in natively. We support Flux and InfluxQL through separate Go processes that use an API to connect to the core DB. Although we're working on native InfluxQL support (it's a Rust based InfluxQL parser that will yield DataFusion logical query plans).

Right now we're focused on our cloud offering. We'll have official open source releases and documentation in the future.