What about a gun license with a gun safety class as a requirement?
Also 4 day waiting list for gun purchases, at this time any red flags when your gun license is scanned gets automatically sent to law enforcement/ fbi so they can do their due diligence without actually stopping anyone from purchasing a gun?
If law enforcement then finds out there's beyond reasonable doubt that you're going to commit a crime then they can act on it. They got those 4 days to assess if you're a threat.
Red flags like mental health disorder, psych meds, watch list, history of dangerous behaviour, etc
Dont know how well this would work, and if it's feasible, but this way no one gets denied purchasing a gun