For those using android, I know most of us or nearly about 70 percent of people who are into Bitcoin investment are in one way having their investments on their phone, while some people have it on their personal computer.
I understand your notion here is very important to privacy
But let me clarify a few things.
Your coins aren't stored in your wallet; they're on the blockchain.
Even if someone should have access to your device, they shouldn't be able to do anything as long as you have extra security measures in place, such as using wallets that support 2FA; we have the Electrum wallet multisig feature and the use of a passphrase on your wallet before a transaction can be performed.
Am not saying we should be careless about our device with a third party, but we can also be faster than any scammer if we put all these in place, and was under attack like this, they can't perform an transaction.
Our password, app freezes, or other security measures we may take in your own approach, OP will only be device-specific, but not protect them from making their way through to perform a transaction unless we have extra security measures in place over our wallet.