Hello forum,

I've already submitted these features to the mailing list:

  https://lists.gnu.org/archive/html/emacs-orgmode/2020-09/msg00628.html

But even if these changes are really tiny and minor, they are touching very 
different functionality of org-mode. It wasn't good mixing my suggestions for 
agenda and for ox-icalendar. So I'm starting a separate mail thread for my 
suggestions.

Changes since v1:
  - Add missing group and type to org-icalendar-*-summary-prepend defcustoms;

Kind regards,
Mikhail Skorzhinskii