is there a wallet design that can allow transfer of ownership of a private key
Discussion
What's the point? If you want to give me all your bitcoin in a wallet, can just transfer everything to my address. If you transfer me just the private key, it's not exactly mine because you also have the private key. If you give me your private key, i will immediately transfer everything away and throw away your private key. Any private keys that is known by a third party are by definition no longer private.
its important if we want to design a better L2 with a federated system that is not mere MPC
What's MPC?
the design currently used by liquid