I would argue that none of this works at all if your computer is hacked. In that case, all of your wallets will be broken into, unless they are hardware wallets.
Why if the wallet file is stored on an external SSD or flash drive? I mean, if the wallet file is stored on a medium that is not connected to the computer, how will the hacker be able to access it even if he hacks the computer?
In this case, storing wallet files separately from the Electrum app is only an initial precaution in case of a PC hack so that wallet files are not directly affected.
Of course, when making transactions and connecting the drive where the wallet files are stored to your PC, you should ensure that the PC is not hacked and is free from viruses.
Hardware wallets can minimize the incident even if they are connected to a PC affected by malware that the user is unaware of. The hardware wallet will have a confirmation process during the transaction, so hackers will not pass this stage easily.
Another example is that you can cancel the transaction if it turns out that the destination address is different from the desired one, for instance, because the PC is affected by clipboard malware.
Or, even if you don't use a hardware wallet, You can use the multi-signature wallet type in the Electrum.