In fact you could do a backup of your GPG key using paperkey and it will be indeed safe on paper.
For your use case I would recommend a Nitrokey Storage 2 because of the following features:
- GPG key on smartcard which is the best possible security
- Password manager for 16 passwords on smartcard e.g. for master passwords used in software or cloud password managers.
- Unencrypted storage that can be made read-only e.g. for safely storing a Linux ISO for booting a trusted environment
- Encrypted storage to hold a backup of your most important files like a password manager database
- Password managers like Keepass could be protected by HTOP generated on the Nitrokey
Backup of the GPG key is also possible with the entry level Nitrokey Start while not using a smartcard, it also stores keys encrypted and secure in the flash on the token. A file or paper backup would be just the same and you could use pass a password manager that encrypts all entries using a GPG key.