will Apple TV 2nd gen support Amazon prime app when it's released, currently running 6.2.1 software?

The older models don't have apps, just preset content sent via server. The 4th gen and newer are the only ones that have access to an app store, with apps developed for the TVOS platform. Also, as the 2nd gen is considered obsolete it has no further updates nor support.

You could still use airplay from the IOS app in the meantime, and the projector should still be fine on the 4th Gen which outputs 1080p, vs the 720p on the 2nd Gen

😢