Thanks for your tips.
My idea was having an iCalendar file, e.g. from Thunderbird/Lightning, and provide the events therein either as a list or as a calendar. The mentioned plugin already offers the capability to do this, it only doesn’t read iCal files. So there’s no yaml file that could be read and I don’t know whether Twig offers the possibility and/or efficiency to parse other file formats.
The easiest solution would be parsing the iCalendar files(s) and writing an according file/folder for each event. My problem with this was that I considered only those event hooks that are fired on every page access. And, of course, it makes no sense to parse and re-write the events on every page load.
But, thanks to your post, I thought about using other event hooks. In the meantime I’m considering
onAdminAfterSave which I could use to parse the iCal file and create a file/folder for each event. This would lead to a one time run of the parsing routine which would be ok for me.
But now I’ll have to test if these hooks are fired when the plugin setting are saved, otherwise this won’t work either.