Hacker News Reader

Telegram has this built-in. The chat list contains an entry called "Saved Messages" that is basically a one-to-one chat with yourself.

I pin the chat to the top for quick access, but one downside is the notes aren't fully accessible offline.

I did similar. It is good for cross platform since I use whatsapp on windows too. Funny how people come up with similar things.

If you add your own phone number to contacts, you can also just start one-to-one with yourself from there