your proposal seems like a lot of mental gymnastics to come to the same result as giving someone the seed phrase to a wallet with the gifted Bitcoin on it?
There's a different risk involved: by giving someone a seed phrase, they may actually start using that wallet, which means you have access to their future deposits. It's much better to teach a new Bitcoin user to create their own wallet, so they know for sure nobody else has access to their seed phrase.
One could argue that it would be better to give them the incentive to learn more about Bitcoin, Blockchain and how to make a wallet and send Bitcoin to that wallet for themselves. It would definitely suit the adoption of Bitcoin better to have informed coiner newbies rather than coiners who only know how to use Bitcoin through third party apps. It would definitely help them out in the long run and learning by doing is really the best kind of learning.
But yeah, unless they transfer the coin to a new wallet there would be a security risk. Again, something the Bitcoin newbies should learn for themselves. But that's just how I think about it.