Yea I feel like it's going to take a few months more of browsing to find all the forum channels I might be interested in and make connections.
(FB also has the same export/feed link, my Android calendar shows my FB calendar as well as my Gmail one, I'm probably going to shovel it all round to NextCloud+DAVDroid to quit using Google calendar)
You can also make use of hubzillas caldav feature. This way you will be able to share your calendar with other channels on your hub.
Is there somewhere similar link for adding it to third party calendars?