Speaker Notes are supported by Hyperdeck. You add them with the Speaker Notes icon:
|Insert presenter notes||Note|
Alternatively, you can just type
;; in the editor. Here is a example of what that would look like in the editor:
;; Ask the audience to raise hands who played Mario Kart before ;; The idea is to lead from playing to the topic # Agenda
Speaker notes are displayed in the moderator monitor below the slide preview.