You can use software that allows you to create a wallet with a seed phrase of 12 words.
It's not impossible to remember 12 words if they are very important. This way you can keep the wallet in your brain. Also known as a bitcoin brainwallet. No one can steal your thoughts.
In cryptography we trust (& verify).
I have considered a 'brainwallet' before but I think the key is to refresh those words regularly
as in to make sure you are remembering the correct words.
In the case of war where you have to vacate you home or that you cannot actually get to
your home a brainwallet is the only thing which is going to save you.
Another idea is if possible create your own seed phrase from a favourite book, say
the last 12 words in the last sentence of the last chapter, all you have to do is remember
which book.
In a critical situation, the last thing I would count on is my memory.... believe me - stress, concussion, injury - and your memory will fail with a VERY high probability. And this is synonymous with “I lost my wallet forever.” It is necessary to have an alternative mechanism for storing critical data - for example, mail systems of large suppliers (Google, Microsoft,...), perhaps (additionally) - trusted people located outside the risk zone. In a word, you need to have 1-2-3 alternative options, in addition to faith in your memory.. As practice has shown, for example, in Ukraine, which is suffering from terrorist attacks on peaceful cities by the Russian terrorist army, our peaceful cities are shelled at night, when everyone is sleeping, and after being hit ballistic missiles into a residential apartment building - you are unlikely to have time to collect a laptop, papers, or anything else to save them... there the question comes in a split second... Terrorists fire volleys at civilians. And if you leave an engraved iron plate at home, and your city is captured, for example, by Russian terrorist troops, your home will be looted, and everyone will steal - wallets, jewelry, equipment, worn underwear, toilets, dishes, anything incomprehensible and beautiful, . .. We came across this... Therefore, I do not recommend considering the option of physical accessible storage.