“Replace ‘firearms’ with any other product...”
Yours is an obvious, but very important point.
Last I heard, the Feds don’t regulate anyone’s vegetable garden because it may indirectly impact on interstate commerce!
You couldn't be more wrong. This whole mess got started with almost exactly that situation.
1942 saw the infamous case Wickard v. Filburn, where Filburn was feeding his own chickens by growing more wheat than he was allowed to do under a wheat price support program. He argued that the feds couldn't regulate what he grew on his farm to feed his own chickens under the guise of the Commerce Clause since it had never crossed a state line nor entered commerce by being sold at all. The Court found against him and brought us to where we are today.
To give you a more current and even more household-scale application of federal hubris, a couple years ago a federal law was passed banning the sale for use by children under 12, of any product not tested and shown NOT to contain lead and some other supposedly toxic chemicals. The feds actually presume to regulate under this law what private citizens can sell at a garage sale, and send around agents to CHECK on them!