hmmm... a planner is one of the few things that i'd like to have access to regardless of what i'm using... One of the few things i don't mind and even slightly prefer to be online first for seemless sync (with the ability to edit and add to offline ofcourse)
Totally get that. I'm planning to support more platforms, and I'm glad to say that iCloud sync is already in the plans for future development.
Local-first should mean that you do have it regardless of what you're using. Point 2 in Ink&Switch's original essay is "Your data is not trapped on one device".
https://www.inkandswitch.com/essay/local-first/