Using non-Google canlendars with KWGT

So I’m running KWGT on a Google Pixel 9 Pro XL, which is running GrapheneOS. Graphene doesn’t have a native Calendar app, so I’m using Fossify Calendar, which is free and open source. I haven’t been able to find a way to direct KWGT to look at Fossify Calendar to get event info though.

I found a Reddit post stating that KWGT draws from the system calendar contract, so if the calendar app syncs with the system calendar, KWGT should be able to access those events.

Might be a big ask, but does anyone know where I would get started trying to get Fossify Calendar and KWGT to communicate?