I can’t recommend Daylio enough! It’s an app that’s constantly getting new features. It’s very customizable! You can make goals and custom moods which both help me a lot. You can also set reminders to do goals or just to make a daily entry. And all your data is stored locally unless you want to backup up to drive. Which is pretty secure. I think I also read that the backup is encrypted but I could be wrong. You can also manually backup and encrypt it then.
Modern cell phones. It’s crazy that I basically never need a computer now. My phone is so diversely useful. I spend more money on phones than computers now. It’s also the best camera I’ve ever had! Phones are just so cool lol.