Bluenote

A simple memo app that allows you to write memos in thread format.

You can change the thread display style by choosing between chat style and card style, and visually customize the memo display to your liking. It also has a trash can function and light/dark mode.
Data synchronization between devices takes advantage of Bluetooth, so it can be done even when offline. Also, because of this mechanism, memo data is only saved on your own device and is not uploaded to the server.