Comment 4 for bug 1813399

So in fact, HKP is quite easy to do by hand, e.g.:

http://keyserver.ubuntu.com:11371/pks/lookup?op=get&search=0x99242560

where 0x99242560 is the keyid field and keyserver.ubuntu.com is the keyserver.

It's trivial to do that yourself in cloud-init, there's no need to involve all the gnupg and dirmngr mess.