She does not assume a power to pardon for state crimes. The main impediment is the practical one, since a vague order regarding victimless crimes may not be enforceable. POTUS has historically granted general amnesties, such as Lincoln's Proclamation of Amnesty and Reconstruction which did not specify particular laws that were violated or individuals who violated the laws. Some degree of resistance to such an order (by prison officials and the judiciary) is to be expected, to the extent that the scope of an amnesty is ambiguous. The Lincoln proclamation is clear enough in its scope (it was triggered by taking an oath of allegiance and the persons to whom this remedy was not available are clearly-enough described).
There are on the order of 70,000 federal criminal convictions with sentencing every year, so probably over a million cases would be subject to review. She would need to sharpen the criteria, presumably by enumerating the applicable statutes. This may include or exclude convictions for perjury or lying to a federal officer. In an individual case, it could be argued that in this case, lying did not violate the rights of another person, but in that case it did – case by case review could be required. Violation of 18 USC 228 (Failure to pay legal child support obligations) might be considered to have a victim, or not, so just saying "non-violent victimless crimes" leaves open the question whether interstate refusal to pay child support is in the pardoned set. Targeted amnesties such as violation of the Controlled Substances Act could be specific enough that they could be enforced.