Create your family chart in the app, print it for the fridge, then keep it current with taps or Siri. Kids keep using the page. Android follows Play Store readiness.
The paper stays. The parent phone keeps up.
Six is the age the chart starts to work without a fight. Make the bed, brush teeth, pack the backpack, set the table, tidy the play corner, feed the pet, help with dishes on a good night. Big enough to read the words, young enough that the star column should stay simple.
Five to seven. Enough that there is a star to chase, few enough that the page does not feel like homework. The morning routine takes three rows; the rest of the day takes the rest.
Stars are a record, not a currency. Use them to see what happened during the week. If your family pays for bigger extra jobs, keep that rule separate from ordinary family responsibilities.