I made a notes app that's kind of like that. Notes get added to the top and when you edit a note it gets "bumped" to the top again: https://thinktype.app/
A web page that can run offline is typically called a web app. With some metadata it is possible to "install" them to run in ui chrome less windows like a natively installed app on multiple environments.
It's not the .app domain so much as the functionality. Web apps are nicer and easily accessible imo, lower friction than an install. Not everything should need an install.
You're somewhat right. However, I would hesitate to call any website an app. And there certainly is a difference. For one thing I would say an app must be it's own program, even if it just uses Electron or similar.
