A thought experiment i wanted to know.
I have saved it in a disc (was inspired by satoshi who stated it that he has saved it and buried it)
memorised and saved in hdd in air gapped though!
I want to believe you're quite aware of the situation where you does not have access to the keys totally means a denied access to you coins as well, i want to believe in this you're referring to having an hardware wallet or a cold storage whereby the keys are in your possessions, they are actually non custodial and i will drop you with this for more safety:
additional protection for your seed and private keys and also, you can go through this
secured air grip storage method they are recommended means to best save your key.