DAG is just a data structure, IOTA and Nano have very little in common despite both being DAGs. Most attack vectors will be based on the consensus mechanism, which are completely different in the cases of Nano and IOTA. If there is ever a realistic attack vector that is shared by both, it's unlikely to be simply because both are DAGs and will likely relate to some other commonality.
In this particular case, since the attack on IOTA was based on a dependency used by a 3rd party within their wallet, the only way for Nano to also be vulnerable was if some Nano wallet was also using that 3rd party. But this would be true of any cryptocurrency project, any crypto wallet that used that 3rd party (and that dependency in particular) would be vulnerable to the same attack vector.