This feels right for the most part. I like the Google Drive approach but am a bit disappointed, that I cannot view my data there. This would be data export by default and thus awesome.

Export is really important to me to feel safe. Also I'd like to know the business model, which I assume is freemium. The preview has no undo, and ctrl+a and del is one of the first things I did. It works in the app though.

Maybe, you could implement some kind of incremental ctrl+a, so that it first only selects the item you're in - though there are already other shortcuts for that.

Long texts will be broken up into multiple list items each time you use enter. I am not sure, if that can lead to problems later on. So far it does not.

Very well executed, including apps for iOS and Android.