Missing Appstore on 3rd generation Apple TV

The 3rd gen does not run TVOS, it is a more basic firmware, and its last update was from Sept 2021. As above, the 4th gen introduced the App Store, alongside the TVOS platform (which the apps were developed for) and advertised storage (used install those apps).

app store was introducted with appletv 4.

appletv 3g does not have any storage to install apps on