Most safe custody providers use this tech that’s why it’s called ‘cold’ storage. These company won’t reveal the wallet they are using because of security. Experts would suggest wallet to be custom built.
Custody providers operates as team, individual setup don't need a custom built, as may fail to realise faulting after building.
If you want a hardware wallet with cold storage forget about custom set up and fix yourself with what has been and anyone can recommend.
You aren't going to be the first whale investor, how many Bitcoin are you planning to hold that others are not aware of.