A planner app that stores data as plain text or md and has iCloud cal sync?

I’m looking for an app to plan my freelance weeks/days. I’d like it to store data locally / on Dropbox / iCloud and in a way I can access it (plain text or markdown). I’m also after something that lets me see my iCloud calendar events within the app. Another plus would be a one off purchase - not a huge fan of subscriptions. NotePlan is the closest I’ve found but the subscription cost is a turn off. Sunsama is a really great app I think but also an expensive subscription and doesn’t sync with iCloud calendar. I’m currently using Things 3 but it’s really not a planner in the way I want.