It's bare minimal. There's almost nothing to see. You have to opt in to install almost everything, including an app store.

It's pretty much just stock Android without the proprietary Google stuff. You can install sandboxed Google services if you want.

It's better than Android though in the sense that it's hardened. There have been cases of exploits that affected all Android users except those using GrapheneOS. The image crop vulnerability, for one.

What kind of Apps you install, or what app store they have?

What kind of app store you install?