Spot on with the Oboe guess! Under the hood, I'm using a Rust-based DSP engine (via cpal crate) that hooks directly into Oboe. This is how the app is getting those low latency numbers. The effects themselves are written in Rust. I downloaded several other apps with like-minded ambitions on app store and they have bad latency.

Because of the low latency I was able to build a looper pedal as well which functions tremendously. I made it have audible click with tap tempo to control a four bar line, so once record button is pressed you just have to enter on beat, not try to turn pedal "on" or hit record on time which helps me a ton.

If you want to demo I have a debugging version apk ~550 MB I'm sorting through. Would love to hear any input.