Forgotten Tales

I have an idea to facilitate the purchase of extra material so that you do not have to leave the game to buy ...

The issue with this idea (it's a good idea) is that Google sometimes takes a while to tell the game server to add the item to your account. Patience is key for such, and an in-game purchase method will only complicate such issues.
Just my opinion.

I suppose it'd be beneficial to those who make purchases on a regular basis (not me), so the only issue I'd have is if there was a programming issue, as a very broad term.

If purchases were "now" then yes, nice thing. If Possible in the 'programing'.

But purchases at G are not instantaneous, so doesn't make sense, to me, to crowd the screen with another button. Especially since it would shut down the game to go to G anyway.