what about that the main seed phrase SeedXORed into 3 separate seeds. Each XORed phrase stamped in steel and placed in tamper evident envelopes, one secured in a safe at home and the other two secured in trusted entity in different cities.

The XORed seed stored at home also serves as the decoy wallet, which will contain some funds on it for a worse-case scenario.

Encrypted seed on airgapped microSD card, available at home, protected by strong password. Password for encryption password stored on airgapped laptop.

Long passphrase on main seed phrase for the majority of the cold storage funds. Passphrase also stamped in steel and placed in a tamper evident envelope, stored in a safe at a well armed family member's house. This is not stored digitally, even airgapped.

This requires at most 4 separate locations (including home), trusted entity that don't travel often, live outside of the city, and are well armed. Airgapped laptop with local password manager (KeePass-based), full disk encryption with a strong password.

when cross input sig. aggregation into taproot then lets talk about multisig. but its not activated in the current state.