Bluetooth is not recommendable. Better to get a USB hardware wallet, but not still that recommendable, the best is to just make use of QR code while making transaction which is better. Have you seen a device that its bluetooth will always be on? I haven't seen such a device before.
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2. QR codes allow visually representing the same information. Because the transaction is too big for a single QR code, an animated code is used. Again, the information is not human readable, and another wallet is needed to verify the data.
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If you simply try to read the data with a regular QR code scanner, you’ll be none the wiser:
Judging by the article, it's not that easy to verify the QR code after all. Every hardware wallet has its pros and cons.
https://shiftcrypto.ch/blog/does-airgap-make-bitcoin-hardware-wallets-more-secure/