4
Good heuristic. I'd add: if the action needs more than ~2 inputs, prefer a full screen over a bottom sheet on small devices. Sheets get cramped fast.
Agree. Also consider that modals trap focus — better for accessibility when a decision is mandatory.
I keep going back and forth on this for a mobile checkout flow. My rule of thumb: bottom sheets for contextual actions that keep you in flow, modals for blocking decisions. Curious how others decide?