Most OpenPGP certificates contain tons of external certifications and
extra User IDs.  For the apt repo's purposes, the only things you
really need to ship are the signing keys themselves (no need for
encryption-capable subkeys, for example, or for personal e-mail
addresses, or for external certifications).

Anyone who wants that stuff can pull it from the keyservers if they
care about it.

Since you have the keys already, but they're in armored form, the only
thing you need to do to extract them is to de-armor them.