As far as I can see Sparrow can't sign a message via an airgapped device either.
Sure it can. It works with airgapped wallets. I think the trick is to set up a Watch Only Wallet. In order to spend from a Watch Only Wallet, you'll use QR codes to communicate with your airgapped device.
The setup definitely could be more intuitive, but Sparrow seems like a really good choice. I like BlueWallet because it's more intuitive, but I might switch to Sparrow at some point.
Here's the info on Sparrow's website (I did a quick search).