This is how I airgap.
I have a laptop which has never been online. On that laptop I have Electrum. If I need to pull sats out of a cold storage address I'll import that key into Electrum (which has no other balances, hence I don't even need that seed). I create the transaction, sign it and pull that onto an USB drive. Then I delete the address again from the airgapped device. I then open another (empty) Electrum wallet on the online rig and simply broadcast the transaction to the network. Process takes less than 5 minutes.
