During gameplay, both graveyards, decks, land stacks, and opposing hands cannot be selected to view unless you have active priority. Observed on iOS

Steps:
1) Enter game match
2) While opponent has priority, attempt to inspect graveyards, decks, opponent’s hand, etc.
3) Observe: player is not presented with a viewable graveyard/library, enlarged display of opponent’s hand, or spread of stacked lands
4) Observe: once priority is passed back to you, any selected item(s) immediately display