I disagree with you because it would mean that only DYI from scratch devices are able to be considered as airgapped device since there are no means to check and guarantee that a purchased device (or computer) has never been connected to internet and to any network.
In that case, all you need to do is to format the device's hard drives and install a clean os. Actually, you should do this for any device you buy even if you are not going to use it for crypto related activities.
You claim hard wallets give maximum security but they are not airgapped, they need to be physically connected to an online computer, and we've seen that seeds can be stolen by a firmware update.
I didn't say hw are airgapped devices but I said they are better than airgapped phones. I'm referring to reputable hw, ofcourse.
If a device is never connected anymore to internet before being out of order, it can be considered as fully air gapped since even if a malware or a backdoor is present into it it will never be able to send the seed outside of the device.
It depends on the malware infecting the device. Take the clipboard hijacker malware as an example,it can steal your coins without needing to be connected to the Internet.
You can't format all devices and even less installing so-called clean OS on all of them. In addition how do you know your OS is really clean? You'll never be able to guarantee it. Besides that formatting doesn't destroy datas until new datas have been overwritten onto it, and it can't do anything against malicious chips inside your device on top of that, so it's not a perfect method.
"Reputable hardware wallets" doesn't mean anything, Ledger wallets were reputed before they had to admit such vulnerability.
You're right for malwares like clipboard hijackers, they could theoretically mislead you but if you double check the transaction you sign and then broadcast, you can address this risk.