The visual direction every screen in the PRD is designed against.
Mainstream patterns from apps users already know: standard tab bars, list rows, cards and icons exactly where convention places them. Zero learning curve.
Pick the one animation style that gives the whole product its motion feel. A full motion plan is written into the PRD either way.
Motion exists purely to confirm actions and explain change: presses, focus, fades under 200ms. Nothing decorative, nothing that slows the user down.