Not really. Your only current option is to build your own app for your community.
The thing is, delivering in-real-time push notifications requires some work (issuing certificates for specific sites, sharing them between site owners, Apple, Discourse Hub, etc) which CDCK can only do for business clients.
As another alternative, you could suggest your iOS users to use Fig, which does send push notifications, but also imposes slightly different UI.
Or (yet another or) wait until Apple implements push notifs for iOS PWA (people have been waiting for this for, I guess, at least 5 years)