USB connection with hardware wallets is not the same as regular USB connection, but it's true that this can't be considered as air-gapped device, unless USB is used only for charging.
However I don't see big advantage for microSD cards, and I much more prefer QR codes for air-gapped devices, like Passport and Keystone are using.
I agree USB can be a security risk since it's a data connection.
Even more, no matter it's done over USB or on a microSD, regular updates can also be seen as a security risk.
I don't like Bluetooth at all, and I am not a fan of NFC that is just antenna with shorter range, but for everything there are pros and cons.
This is why I am lately very fond of concepts like SeedSigner, although I don't know whether its lack of secure chip can be a problem or not, also don't know if it's overdoing its updates. But at least it uses
images for transferring information.
I also have kinda dilemma about things like SatoChip. NFC doesn't have a big range and the credit cards have shown that NFC is not so badly insecure (I guess that some could counter me badly for this) and it's clearly doesn't need (nor support) updates. So on one side it could be seen as good. Just I can't go over the thing that I feel safe only if I see the transaction on the HW screen. All in all it's somewhere between "very nice" and "no, thank you".
