When I started with the keyresolver for GpgOL I had the idea to use the same resolver in KMail and GpgOL. But I never got around to working on that. The API should be similar enough and I explicitly included the mutliple format support for KMail as I think at least for some users the possibility to send PGP/Inline to some contacts is important and this could even be a feature in the future of GpgOL.
It was also the reason why I initially had the "nagging" in API of the keyresolver as KMails Keyresolver also checks for expiry dates of used certificates etc. Something like that would be useful for GpgOL, too.
Anyhow. Since we have the group support now in Kleopatra and in the keyresolver this is more important as that is a killer feature which is often requested. So I add the gpgcom tag as this work would benefit both GpgOL and KMail.