-snip-
And perhaps it's also possible, or necessary to store individual private keys in text on a seperate device such as an encrypted USB stick?
If you're using a descriptor wallet, you can use
listdescriptors "true" and paste the result to a txt file then encrypt it.
Those descriptors can be used to import your master keys to another wallet using
importdescriptors command.
But there's no advantage on doing that over backing-up the wallet.dat file itself.