OGG is the free spirit of audio: open, patent-free, and quietly brilliant at looping game sound. It was born in 2002, the Xiph.Org Foundation, and its real weak spot is everyday device support: car stereos and Apple hardware mostly shrug.
WEBM is video the way browsers like it: open, royalty-free and built to stream. A Matroska-based container restricted to VP8/VP9/AV1 video with Vorbis or Opus audio. That makes it the right destination when what you need is embedding on the web without licensing worries.