

Do you signal before you observe what may or may not be where you are wanting to go? Maybe I’m doing it wrong, but I don’t signal until I’ve observed where I’m going and determined if it can be done safely. People driving for miles with their turn signal on make me worried (you can never tell if they are planning to go now, later, after their invited, or if they just forgot it was on).
I know you mentioned Nextcloud and if you happen to already be running it you can use the add-on/module/whatever called Secrets, its exactly what you describe. You make note, send link (can password protect if you want) and once its been viewed its gone.
If you don’t already have Nextcloud, check out vaultwarden’s (bitwarden) send feature.