Anyone keeping an updated blockchain on their airgapped laptop?

A lot of folks seem to have two laptops running Linux, each with their preferred distro. The one that signs transactions is totally cut off from the internet, no wifi, Bluetooth, or any wireless stuff. This cold wallet laptop doesn’t have an updated blockchain. If you're using Bitcoin Core, I guess you just install it, open it, and let it sit there like it’s trying to sync, but since there’s no internet, it never actually does, and then you create a PSBT file to move over to the other laptop that has a watch-only wallet with the blockchain synced, and then you can broadcast it. But here’s the thing: I always thought the hot wallet laptop looks kinda weird or just plain disappointing. It shows zero funds and is stuck trying to sync, but since it can't connect, it’s just sitting there doing nothing. What if you copy the blockchain files from the hot wallet to the airgapped laptop? That way, you'd actually see your funds on the airgapped one too, which would be way better than seeing zero BTC. I mean, I get that it’s just a mental thing because the hot wallet shows the right balance, but if that airgapped laptop has extra space, why not throw the blockchain files in there for good measure? It could also serve as a backup. The tricky part would be transferring those blockchain files safely to the airgapped laptop. USB sticks might carry risks of infection. There are other options, like optical disks. Some larger capacity disks are available that could be a smart choice for backups. Last I checked, you could still write to these disks.

Transferring blockchain files will always force you to do this every time you want to spend, but why do you need to do that when you can import your MPK to full node/ SPV wallet? Instead of using flash memory, CD or USB disks, you need to install a camera in the airgapped, sign the message, show the QR-code, broadcast the transaction, and  you will be 100% guaranteed that there are no viruses or weak spots in the airgapped system. There is a case in which you do not need to synchronize, which is if you use the Send All feature.

Isn't that the point of using an air-gapped device? You're not supposed to daily drive it and make it work on something every day. I honestly think there's nothing wrong with that, as offputting as it is for you. The priority is the security of your wallet, which is why I don't think most people would recommend you buy a $1000 laptop just for that. If you don't have the funds to buy a separate device, what about using a live OS to manage your funds? You'll need a USB stick too, after wiping it and installing an OS of your choice. I don't think it is as secure as an air-gapped device though, CMIIW.

Your question is a paradox in 2 places. First is obviously the fact that when you say "cold storage" and "airgap" it means absolutely no connection to the outside world. Be it an internet connection or you connecting a USB disk, putting in a CD and regularly transfer files to that system, in which case it stops being "airgapped". Second paradox is that when you say "cold storage" you are talking about a key storage not a "coin" storage. Which means it is only supposed to store your private keys and not your coins to know the balance. In fact I'd argue that the client should not even show a balance box in UI. Instead it should show you the number of private keys/addresses that the wallet holds.

"No connection to the outside world" sounds a bit of an absolute. If there is no connection to the outside world, then how can you make and transfer transactions with it? Instead, I'd rather say "being airgapped means incapable to connecting to any network". Having a wireless network adapter, even if disabled from your operating system, does not make a machine airgapped. However, being able to transfer text in the form of QR codes, does not connect my machine to any network, nor does it allow the network connected computer to infect it in some manner. Plugging USB sticks back and fourth is quite hard to decide if it passes the test, because it does not connect the computer to a network, but it might be able to infect it somehow if the network connected one injects a malware. Maybe a security expert can clears this out.

The function of a airgapped device is to store your keys which can be used to sign your transaction. If you do what I quote, your airgapped wallet is no more airgapped as long as you do not see 0 BTC anymore. If you have a wallet on an airgapped device, you will have a watch-only wallet on another device which you will use to track your coins. It is also worth knowing that your coins are not stored on your wallet but rather on blockchain.

Cold wallet on airgapped laptop doesn't need any blockchain data, actual or past, to function in accordance with its assignment which is to sign raw transaction created by hot (watch-only) wallet and send it back to online device. The latter pushes  signed transaction alone. Thus the copy of actual blockchain would "contaminate" the airgapped  machine with unnecessary (and might be dangerous)  data.

It's a feature, not a bug. If you want to have a secure air gapped system, you'll have to put your mind over such tiny inconveniences.

On Linux, you could explicitt disable autorun when you plug USB drive and use noexec flag when mount the drive to partially prevent binary on that drive being run[1]. [1] https://superuser.com/a/1276936