Looks really cool! For anyone looking for a very similar UI but an editor that also supports complex blocks (like Kanban, images etc) you can check out my note-taking app Plume with a block editor[1] (beta is out in about a month, sign up for the waitlist!). Every note is a simple plain text string (with Markdown syntax) that is rendered via Qt C++ and QML.
[1] https://get-plume.com/
EDIT: Added the app isn't out yet (about a month more of hard work!)