A) You cannot store sats offline, they never leave the ledger or it would break

B) You don't need a signing device to store a private key offline.

Just backup the key from your wallet and put it on any medium you deem appropriate. Three pen-drive (in case one breaks), metal cold storage card, tattoo under your lip etc etc. If you then want to ever access those coins on the blockchain you'd simply import that private key to a wallet (such as Electrum) while disconnected from the internet. You sign create your transaction and sign it. Then you take the transaction to an online device and broadcast it to the blockchain. done.

After that you can delete the key again from your wallet.