MicroSD with encrypted seed backup (7zip, AES-256) - generated from Coldcard, protected by 12 words, never to be inserted into anything other than Coldcard, or Tails (in case of emergency)
Coldcard Mk4
Passphrase (six BIP-39 words):
Keeping in memory
DIY Stainless Steel Washers
Password manager, archived and stored under random name
KeePassXC vault inside of a Cryptomator vault stored in multiple cloud services and local flash drives
Standard Notes protected note
12 words for encrypted backups
KeePassXC vault stored in multiple cloud services (different from ones storing the passphrase)
I keep separate accounts for KYC, "Light" KYC, and P2P No KYC.
All other wallets are derived using BIP-85 from seed+passphrase as a master parent seed.
All online services are protected by YubiKeys or YubiKey Authenticator 2FA TOTP codes and very strong diceware master passwords.
Not ideal, probably too many backups, but I'm still learning. Will be moving to multi-vendor 2-of-3 or 3-of-5 multisig in the future, when I get more comfortable with it. And I should probably delete this comment soon.
Seed backup:
Passphrase (six BIP-39 words):
12 words for encrypted backups