Can we get an in-game sticky note/reminder function?

[Iscah]

/echo just sends it to your chat, not the party chat. You'd need to use /p for that to happen.

You don't "need to use /p" to accidentally send things to party chat - you just need to forget to put something else.

Is there a way to write that where I don't share my note with the party when I click on it?

The easiest way is to set up your "sticky note" macro in advance with /e (for "echo") at the start of every line to ensure that particular line will always display as echo text regardless of your current chat channel.

I have a blank one saved as a template and I'll copy it to another slot if I want to start taking notes.

[Mhaeric]

You don't "need to use /p" to accidentally send things to party chat - you just need to forget to put something else.

And for my tangentially related nitpick to your tangentially related nitpick, that is only the case if your default chat is set to party.