I use Tasks.org android app on my phone’s home screen that displays Appointments with 3-days before, 1-day before and 8-hours before reminders, unscheduled To-Do tasks and Shopping/Grocery needs.

All other notes are kept using Termux where I can sync my notes with my computer using rsync.

It took me at least a year to get into the habit of using my notes and reminders like that but it’s worked great so far.

The only downside to my system is that if I lose my phone, all my appointments will disappear into the void. Win some, lose some. Fortunately I keep a simple life which reduces the chances of unwanted human contact appointments.