As long as your friend has a computer capable of running iTunes, go ahead.
The friend will have to redeem it in iTunes and download it in iTunes. Then they can copy the downloaded file to their Android (or upload it in to the Google Play Music website,) and it will play just fine on an Android device.
They do have to have iTunes installed somewhere, and they will likely have to make an iTunes account if they don't have one already, though.
Note: I have music purchased on iTunes, Microsoft Xbox Music, Google Play Music, and Amazon. I have all of them available in every service, using the various "automatic uploaders" they all have available. So my entire music library, regardless of where I purchased each individual song, is available on my Windows tablet, my Android tablet, and my iPhone. (Xbox Music is by far the most difficult to deal with.)
The friend will have to redeem it in iTunes and download it in iTunes. Then they can copy the downloaded file to their Android (or upload it in to the Google Play Music website,) and it will play just fine on an Android device.
They do have to have iTunes installed somewhere, and they will likely have to make an iTunes account if they don't have one already, though.
Note: I have music purchased on iTunes, Microsoft Xbox Music, Google Play Music, and Amazon. I have all of them available in every service, using the various "automatic uploaders" they all have available. So my entire music library, regardless of where I purchased each individual song, is available on my Windows tablet, my Android tablet, and my iPhone. (Xbox Music is by far the most difficult to deal with.)