Instead of the luks key in tpm you can use a fido2 compatible hardware security usb token. For booting/unlocking it has to be plugged in then you can remove it.

Instead of the luks key in tpm you can use a fido2 compatible hardware security usb token. For booting/unlocking it has to be plugged in then you can remove it. This is pretty convenient and secure against many threats like stealing the nas in my opinion.