Hardware wallets like Trezor and Ledger are terrible choice for privacy as they’re more like hot wallets. You need to download their shitty electron app to configure your wallet and even if these apps are open-source I can’t consider them safe, because they have toooooo much features. At the same time they’re missing basic features like connecting through TOR network to them which should be must have as they rely heavily on internet features like online exchanges which can easily reveal your data. Do you have any idea how to access crypto easily while at the same keep it private and safe?

What you really need is an air gapped or cold storage and you can achieve this in many ways. I found that one of the best ways to do it is grabbing an old phone and following this guide. TLDR: install the software wallet and never connect the phone to the internet again and use QR codes to sign transactions using the camera. Practical, cheap, truly air gapped and doesn’t attract attention like a hardware wallet.

If the air-gapped phone is stolen, is guessing the PIN to unlock the phone the only thing stopping the thief from spending the victim’s money at that point?

There are a couple of things you can do: Hide the app from the app drawer. To open the app you have to go to settings and look for the complete app listing which include system apps. Search how to hide the app for your particular android version. Connect the phone to the computer and install the wallet as a system app using adb. Being a system appt you can disable it from the app’s context menu and the app will not be visible. To open it you have to enable it from the settings. In both cases is extremely improbable that someone that grabs it will start to look for hidden or disabled apps in an old and seemingly discarded phone. That’s why NOBODY has to know that you save your keys in this way. Just grab an old phone, the older, cheaper and unatractive the better. Nature teaches us that disguise is the best way to hide. And in case is stolen, you have a good amount of time to move your coins to another wallet.