Quickset

QuickSet gives you a randomized bodyweight workout in one tap. Pick a mix of push ups, squats, planks, and other simple movements, each with a randomized rep count or duration, and get moving in seconds.

There's no account to create, nothing to sync, and nothing tracked. The app works fully offline and asks for zero permissions. Tap the button, do the workout, close the app. Tap it again tomorrow for something different.