Louferlou on Nostr: Yep basically you need your original seed phrase safe in your microSD+written down, ...

Yep basically you need your original seed phrase safe in your microSD+written down, to have access to your initial wallet. And you need to remember/write/backup your passphrase like a 25th word, to access your new wallet.
With this done you can create as many “hidden” wallets, each one associated with a specific passphrase with the same initial backup engraved in steel and hidden in many places or whatever. Just don’t forget each of your passphrases.

I would recommend to move all your mixed UTXOs one by one on your new wallet, and keep your KYC UTXOs on the older wallet for example to keep them apart.