You can tell how long a key is just by looking at it. You can then say anything you want. The use of particular keys is a Debian policy issue. It has nothing to do with the use of a particular message format like OpenPGP.

That's not how it works, no. This is a gpg specific issue as it does not communicate the key size over the status fd.

We don't parse the keys ourselves for obvious reasons.

Dunno about that but --with-colons certainly works to show the key length of a key.

i am pretty sure you can mark them yourself. but that they are generally still used, well that's called backwards compatibility. and that's needed.