This is generally good advice. It never hurts to be careful and it’s really important to learn your local, state, and federal laws so you don’t get entrapped or otherwise fucked.

But generally speaking, in my experience in the US at least, getting a gun is very easy. Gun ownership is so ubiquitous that buying and owning a gun is very unlikely to trigger any flags or problems (assuming you aren’t a felon). In many states, local law enforcement aren’t involved at any step of your gun purchase and have no easy way of knowing you’re armed. The background check is a short call to the FBI and the form you fill out often stays there in a filing cabinet at the store / FFL until it gets requested for some reason. Getting a CCW license, for states that require it, may involve a short interaction with a sheriff or other LEO, and may put you on a list (a large one with tens of thousands of people, in most states at least). But I’d recommend a person be proficient with a gun before they start carrying it, if possible.

Having friends who are experienced with guns is probably the best. Joining an org is generally a good idea but probably much higher risk of putting you on a list than simply buying a gun. Taking classes and practicing is highly recommended, if possible. But none of that is necessary for just buying a gun. And as shit continues to get worse, I’d rather comrades at least have access to a gun, even if they just lock it in a closet, than never get around to getting one until it’s too late. Obviously train with it now, if possible-- the best advice is to get one and train with it. But you can’t train later if you don’t even have one in the first place.