Start with the actual task
Navigation, browser search and internet messaging need data rather than a Korean voice number. Write down any reservation, delivery, local call or verification step that specifically asks for a domestic number. If no step does, a data-only option may be the simpler setup.
A number is a product feature
eSIM describes how a plan is installed, not whether it contains voice, SMS or a Korean number. Both eSIM and physical SIM products can differ. Check the live inclusion list rather than treating ‘eSIM’ and ‘data-only’ as identical labels.
Keep a no-number fallback
Store accommodation details in Korean, use official tourism help channels when appropriate and confirm contact methods with any booked provider. Never publish your temporary number, passport image or activation QR code in a public trip planner.