Not true.
How do you think sanctuary cities for illegal; a;iens were created.
Federal Officers were not allowed to access any illegal aliens through the state systems. They walked.
The same would be organized around federal firearms offenses. Without state justice system cooperation, the majority of those otherwise subject to federal firearms laws will walk.
The result is just like happe4ned in sanctuary states for illegal aliens, with no cooperation from State LEOs or Sheriffs.
Only because the FEDs don't have the will to enforce the law there. Similar with pot laws. The FEDs selectively enforce.
The government has an intense animosity toward the right to keep and bear arms. Whatever "support" it claims to have is a sop. There is no way a state law will deter the FEDs from targeting gun owners.