I don't think that would be a beneficial means of attacking the problem. I just can't imagine that working very well. If you loaded up a tumbler with pins, most of them would be very lightweight and in numbers, they would just knit themselves into a mass that would sort of protect the individual pins from being struck by the (in this case) ceramic balls. And the balls would have to be of small, tiny diameter, thus they wouldn't hit with much force. I don't think you could even count on the gold plating being "knocked off".
No, you need the 100% contact of the pins being immersed in a liquid.
You are absolutely right to respect the hazards of some of the chemicals and some of the chemical reactions. No two ways about it. For me, myself, I have come to the conclusion that, particularly in light of the amount of materials I can reasonably expect to gather, I cannot set up an acceptable lab that I can leave undisturbed, with a means of evacuating vapors and providing a place to melt materials and otherwise providing for safety and storage of hazardous containers of wastes. I have thought long and hard about it and that's just the conclusion I've come to, speaking for myself only. You know, the flipside of that conclusion is, if there was an functional way to gather, process, recover and refine the metals that DIDN'T use hazardous and expensive acids, arcane glassware, and all manner of safety gear, you gotta know that the experienced members here would eagerly try them and use them. This ain't the "Fun with Nitric Acid" forum, LOL.
That absolutely does not mean you cannot learn about the techniques and perhaps more importantly, gather the raw materials from which posters seek to recover and refine PMs and profit therefrom. I'd be very comfortable saying that among the posters on this forum, as a group, the ones who simply gather materials and ship off to someone else to refine make as much money as the ones who actually refine and melt. And if you took out Lou, 4metals, and a small handful of other professionals whom we are very lucky to have in terms of their experience and insights, the sender-offers would make more.