> or (the better solution) just enroll your own certificate in your TPM and sign the driver with that...
I'll tell Grandma that's what she needs to do.
Why would you put Grandma on VeriCrypt in the first place? It's the more 'difficult' option for FDE.
your grandma is probably fine with BitLocker....
Make sure that she setup a PKI infrastructure to manage certificate revocation as well, wouldn't want a bad grandson to mess with it.