In most cases, SDFP requires the use of a Magic Band
that must be linked to a profile in MDE, a party ticket card
that must be linked to a profile in MDE, or a room card or ticket card
that must be linked to a profile in MDE. The only medium that does not have to be linked is a card that has never been linked to a profile in MDE. Unless you are using the latter, SDFP necessarily requires use of an MDE account. According to the Terms of Use quoted above, you cannot "make FastPass+ selections" (not just "pre-book", but "make" selections) unless you are using the same admission entitlement that you will use to redeem the FP. That, together with the fact that every page on the MDE site that mentions FP+ states "Valid Theme Park Admission Required," means that using anything linked to an MDE profile other than the admission entitlement that you used to enter the park in order to "make" and redeem a FastPass+ selection is a violation of the MDE terms of use. Arguably, the only exception would be using a card that has not been linked to a profile on an MDE account as that would not be subject to the Terms of Use for MDE.