> Yes, but they're not called .ogg files.

Thanks, I wasn't aware of this. As it seems, recommended file name extensions for audio codecs inside Ogg container are as follows:

Speex: .spx
Vorbis: .ogg
Opus: .opus
FLAC: .oga

(Other than FLAC, .oga files may as well simply contain uncompressed PCM audio.)

Confusingly enough, Wikimedia seems to handle it differently from the Xiph.org recommendation, with .oga being the file name extension for everything Ogg audio no matter the specific codec:

"Ogg-container (using FLAC, Speex, Opus or Vorbis codecs with file extension .oga)"
https://commons.wikimedia.org/wiki/Commons:Project_scope/Allowable_file_types