I use something similar, but it leans on at(1) to popup reminders at predefined intervals. I tend to forget things once I'm buried in my Vim window.

https://github.com/jvinet/dotfiles/blob/master/bin/rin

Examples:

  $ rin +30 Check the turkey
  $ rin '14:30 tomorrow' Watch baseball

I currently have it setup so it pops up a modal dialog using Zenity. As well, it uses my cheap-and-cheerful bespoke notification doohickey that I have running in waybar, another script called notify: https://github.com/jvinet/dotfiles/blob/master/bin/notify

This way, I have a nagging badge/icon in my waybar system tray until I finally do check that turkey and watch that baseball.