One will give you interest on your money only if - in a way or another - he can earn something from that. Since Bitcoin doesn't allow staking, I don't see any ways one can earn from those bitcoins without having access to your funds - usually with you sending the money to the custodial platform. At that point you own ... an account. No "for your eyes only" private keys.
So no, this cannot work on Bitcoin.
And.. from what @nullama has posted, the amount of money can decrease. This means:
1. They do have full access to the funds.
2.
OP needs to improve his understanding over how Bitcoin works, else he may - sooner or later - get scammed by this kind of "wonderful" offers.
Haha i hear you man i am always learning. This project intrigued me but its seems to good to be true and not possible.