Is there a command to tell me what type of metadata container is using a file?

Something like: command myfile.flac saying: vorbis comment or id3v2.

Warning: One audio file can have multiple metadata containers. So finding vorbis comment doesn't mean there is no id3 tags. Reminder: flac and ogg should be used with vorbis comment.

Vorbis comment

Flac

metaflac --list myfile.flac

It will print a lot of info for each block. Here is the answer:

METADATA block #2
  type: 4 (VORBIS_COMMENT)

To install metaflac: sudo apt install flac.

Ogg

vorbiscomment file.ogg

It will output something like:

encoder=Lavc57.107.100 libvorbis
TRACKNUMBER=1
title=My file title
...

To install: sudo apt install vorbis-tools

ID3

Well, the best thing I found is a python library: mutagen. For example, in your python file you can write:

from mutagen.id3 import ID3NoHeaderError, ID3

try:
    tags = ID3("path/to/myfile.ogg")
    print("ID3 tags found: ", tags)
except ID3NoHeaderError:
    print("No ID3 tags")

Output for file with ID3 tags: ID3 tags found: {'TIT2': TIT2(encoding=<Encoding.UTF8: 3>, text=['my new title'])}. It works also for flac files.