Ive worked with events in Kirby a fair bit, including using Fullcalender to display events created as pages within kirby and those coming in from a Google Calender. Fullcalendar only works with public calenders. If the outlook calendar needs authentication like a login or something, then you are out of luck.
I think your best idea is to use a PHP library (like this one https://libraries.io/github/OzzyCzech/icalparser) to turn the events into virtual pages. You can then feed those into Fullcalender.
You might find two of my plugins useful…
Gets recurring dates from between a range (so for example if an event always happens on every second tuesday of the month, Recurr will give you the dates of all of those tuesdays for as a many months and years as you need.) It can also turn a date into a Recurr rule that Fullcalendar understands.
Yasumi will get you all the dates of public and religious holidays for any country in the world and for any year. You can plot these on the calendar.
I hope that helps.
p.s i made this for kirby 2, but it is a working example using kirby pages as events, mixing them with Google calendar events, and displying both on Fullcalendar. Maybe theres something useful in that you use for your project. (note that there is now a decent GCal plugin for Kirby 3 so you can use that instead of all the manual API stuff in the repo below.)