I wouldn't say everything is that experimental. I've been using nimx for android in production since 4 years ago, and I've got crashlytics integrated, so I kinda have some idea :). Java-nim memory model is pretty well defined in jnim, and it just works with nim default GC. The only thing experimental in jnim is jni_export which allows implementing Java classes. Including the main activity btw, so no need to stick to NativeActivity.
@GordonBGood offtopic, but i've got a wasmrt and jsbind projects which demonstrate binding to surrounding js environment without external js glue. Now to the point. I don't know what's the exact problem you're hitting now, feel free to demonstrate it preferably with steps to reproduce. Also feel free to DM me on gitter or telegram for more streamlined communication.
