What are you talking about? How do you get your crypto on an "offline physical device"?
It's a bit of a farcical concept in cryptocurrency. There's two keys to a wallet, which are analogous to public and private keys (because that's essentially what they are). They look like this:
Wallet address:
1JxjwrbA8VdRnX2yRcp5HXGiKX2QcKBE2
Spend key:
Kxvb4FcVEZPj7xvyrP5N5BxRLE6NfohWjuAjtnCz2aC9pJgP8djC
Technically, you can keep the spend key safe however you like. Print it out and stick it in a physical safe, and now you've got an offline wallet. Problem is, if you actually want to transfer any coins from that wallet, you'll still have to enter it into a computer at some point and it could potentially be compromised.
There are also hardware companies selling overpriced "wallets" which are glorified flash drives to store the same sort of information I've just posted above. That's companies attempting to cash in on the crypto gold rush, basically. Your coins are actually located on the blockchain and all any wallet device is ever going to store is just the keys.