I'm working on quick capture! Just a prototype so far for saving text snippets: https://wonger.dev/posts/in-the-works#gimme-that

Ideally, note capture is as easy as screenshots. It means removing nonessential menus, decisionmaking, buttons, etc. For example, having the app start with an editor and keyboard open, versus having the app start with a list of existing notes. It may mean gesture shortcuts.

For a published app with adjacent ideas, check out Bebop for iOS: https://www.jackcheng.com/bebop-design-dev-process/