May state law doctrines of judicial convenience be raised against a preemptive federal statute?

QUESTIONS PRESENTED 1. May state law doctrines of judicial convenience, like res judicata and collateral estoppel, be raised against a preemptive federal statute, 38 U.S.C. § 5301, which voids from inception any and all agreements made by a disabled veteran to dispossess himself of his federally protected veterans’ benefits ? 2. Even if a state court may raise such state law doctrines, may a disabled veteran be compelled by a state court to use his restricted disability benefits to satisfy such an agreement, where 38 U.S.C. § 5301 explicitly prohibits the state from using any “legal or equitable” process whatsoever to dispossess the veteran of his personal entitlement and applies to all such benefits “due or to become due” and before or after their receipt by the beneficiary?