Wouldn't a fresh install of WIndows 10 on a removable SSD which I only put in the computer to access wallets be secure enough? I could keep copies of all seeds in safety deposit box at bank.
Any other ideas? How about my old android/apple phone I am not using? I could do a fresh install on it and only use it for wallet then power it off when not using.
An encrypted USB drive (e.g. Kingston DataTraveler Vault) that has the excel encrypted file containing your private keys, seed keys, wallet info, etc.
Make 3 copies, 2 are offline wherein, 1 is updated weekly, the other 1 updated monthly.
Last 1 is your active copy being used daily.
Note: all are encrypted USB thumbdrives + encrypted excel files