We just bought our 10 year old daughter an acoustic guitar. Neither my wife or I have any musical talent. I see that you can use Garageband to tune an electric guitar. Can I do the same for an acoustic guitar using the built-in microphone?
No you don't the tuner has a needle to tell you whether you are sharp or flat or on-pitch. No musical ability required.
You can certainly start with GB, and if it proves inconvenient for your daughter to interrupt your on-line game to tune her guitar,
then you can get the stand-alone tuner.