Please have open feeds in iCal format for your site, including one that lets people get all public data.
This will make the data on your website so much more reusable and useful.
And definetly iCal - it's so popular, and most personal calendars can even import it directly.
Yes, it's odd text format is a pain, but there are libraries in almost every language you can use.
Mobilizon has iCal export for a single event, but not for all public events on the site. (I did have a Mastodon chat with them about this but can't find their replies now)
But definitely congrats to Framasoft for this :-)
0: https://yggdrasil-network.github.io/