Questions regarding best method to buy BTC for my younger brother

Hey all,

Im trying to help my brother out who is 17. Currently he is buying Bitcoin on Cashapp, doing DCA daily with about $5-10, and I just made him a new wallet on Exodus to send the Bitcoin over to the wallet because he wants to create a new Cashapp acc. I told him to not buy BTC off Exodus because the fees are quite high compared to what I pay for on Robinhood. Because Cashapp knows he is underage, it does not permit him to send the Bitcoin to another wallet address, he will just have to keep it in there or sell it at a very small loss. I do the same thing, I just started to buy $5-10 daily on Robinhood, which now has lower fees than buying on Cashapp, and after a couple weeks I will initiate the first send to my Ledger hardware wallet.

I was thinking that I may have to be buying his Bitcoin everyday for him and sending the money to that wallet I created for him, but I tried to just see what the fees are for sending, say $80 worth to my other wallet and its about $3.40. It isnt super ideal for doing DCA which im realizing, but I was wondering if this is the best route or there is a better alternative. I either buy him $70 worth of Bitcoin every week, and hold it a month and then extract to his wallet? Or is there another way he can buy Bitcoin being underage, as this would be best case scenario for me to avoid confusion mixing my BTC and his up and having to constantly buy and send it to him.

I would perfer a way to avoid paying such high fees while I am sending to my own Ledger wallet, and if I do stick to buying for him in Robinhood, I dont have a clue if it is smarter to hold it for a month and let the amount accumulate before sending to avoid more fees. Do the network fees stay around the same price for sending small amounts and larger amounts when I am sending to the other wallet?

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Hope my question(s) are not too confusing, any help and advice would be appreciated! Thanks!