Hi, all!
I've just pushed a PR with a working version of the new GeoJSON export type for Briefcase. If you want to try it, you can use this JAR file: https://github.com/opendatakit/briefcase/files/2499280/briefcase-geojson.jar.zip
Any feedback will be very valuable! You can write it directly to the PR: https://github.com/opendatakit/briefcase/pull/669