I wanted a way to track when I need to water my plants. I tried building a hardware device for this, but it turned out to be more challenging than expected. After the first iteration I had to reorder different components and rewire it for a better prototype, which didn’t feel particularly exciting. So I built a web app.
It works great.
See it here: https://nkorobkov.com/one-click-routine/
I run it on my second phone as an always-on display in my kitchen.

To make the webpage behave like an app, I use Safari’s “Add to Homescreen” function. To keep it always on, I enable “Guided Access” in the iPhone settings menu.