Oh, wasn't understanding what you mean with air gapped, thought you were talking about air gapped TX signers. You don't need a mobile, I mention them because they're the most common thing around, yet, without resourcing to mobiles: For read QR codes A webcam + QtQR (cost of a webcam starts from around $5 - thus this is normally a 480p webcam and you will immediately find why the QR size matters). A 2D Barcode scanner + any text editor; cost around $15, those scanners, that you normally see in supermarket cashiers, are just "fast" keyboards, they just type really fast the barcode contents. Your own eyes, if you want to waste time know how to read a QR - that's just an alphabet, a bit complex one, like chinese, but you can learn to read it - , and here size will count even more. For RFID (NFC) An USB reader will be around $10 and a reader/writer around $20. For software there's nfc-tools For destruction QR's are printed in common paper, use a paper shredder. If you happened to engrave them in metal or wood, burn the wood and make sure it completely turned into hash or melt, burn with acid or shred the metal (metal shredder cost: > $1.000). RFID, make sure to break its chip and antenna. *metal option would be the same if you engrave the words themselves, except you'll have a smaller area to burn with acid, if that's your option. QR and RFID also don't come with internet connections, nor the internet is your only enemy when it comes to store a backup.
Oh, wasn't understanding what you mean with air gapped, thought you were talking about air gapped TX signers. You don't need a mobile, I mention them because they're the most common thing around, yet, without resourcing to mobiles: For read QR codes A webcam + QtQR (cost of a webcam starts from around $5 - thus this is normally a 480p webcam and you will immediately find why the QR size matters). A 2D Barcode scanner + any text editor; cost around $15, those scanners, that you normally see in supermarket cashiers, are just "fast" keyboards, they just type really fast the barcode contents. Your own eyes, if you want to waste time know how to read a QR - that's just an alphabet, a bit complex one, like chinese, but you can learn to read it - , and here size will count even more. For RFID (NFC) An USB reader will be around $10 and a reader/writer around $20. For software there's nfc-tools For destruction QR's are printed in common paper, use a paper shredder. If you happened to engrave them in metal or wood, burn the wood and make sure it completely turned into hash or melt, burn with acid or shred the metal (metal shredder cost: > $1.000). RFID, make sure to break its chip and antenna. *metal option would be the same if you engrave the words themselves, except you'll have a smaller area to burn with acid, if that's your option. QR and RFID also don't come with internet connections, nor the internet is your only enemy when it comes to store a backup.

Oh, wasn't understanding what you mean with air gapped, thought you were talking about air gapped TX signers. You don't need a mobile, I mention them because they're the most common thing around, yet, without resourcing to mobiles: For read QR codes A webcam + QtQR (cost of a webcam starts from around $5 - thus this is normally a 480p webcam and you will immediately find why the QR size matters). A 2D Barcode scanner + any text editor; cost around $15, those scanners, that you normally see in supermarket cashiers, are just "fast" keyboards, they just type really fast the barcode contents. Your own eyes, if you want to waste time know how to read a QR - that's just an alphabet, a bit complex one, like chinese, but you can learn to read it - , and here size will count even more. For RFID (NFC) An USB reader will be around $10 and a reader/writer around $20. For software there's nfc-tools For destruction QR's are printed in common paper, use a paper shredder. If you happened to engrave them in metal or wood, burn the wood and make sure it completely turned into hash or melt, burn with acid or shred the metal (metal shredder cost: > $1.000). RFID, make sure to break its chip and antenna. *metal option would be the same if you engrave the words themselves, except you'll have a smaller area to burn with acid, if that's your option. QR and RFID also don't come with internet connections, nor the internet is your only enemy when it comes to store a backup.

Oh, wasn't understanding what you mean with air gapped, thought you were talking about air gapped TX signers. You don't need a mobile, I mention them because they're the most common thing around, yet, without resourcing to mobiles: For read QR codes A webcam + QtQR (cost of a webcam starts from around $5 - thus this is normally a 480p webcam and you will immediately find why the QR size matters). A 2D Barcode scanner + any text editor; cost around $15, those scanners, that you normally see in supermarket cashiers, are just "fast" keyboards, they just type really fast the barcode contents. Your own eyes, if you want to waste time know how to read a QR - that's just an alphabet, a bit complex one, like chinese, but you can learn to read it - , and here size will count even more. For RFID (NFC) An USB reader will be around $10 and a reader/writer around $20. For software there's nfc-tools For destruction QR's are printed in common paper, use a paper shredder. If you happened to engrave them in metal or wood, burn the wood and make sure it completely turned into hash or melt, burn with acid or shred the metal (metal shredder cost: > $1.000). RFID, make sure to break its chip and antenna. *metal option would be the same if you engrave the words themselves, except you'll have a smaller area to burn with acid, if that's your option. QR and RFID also don't come with internet connections, nor the internet is your only enemy when it comes to store a backup.