I saw these being talked about on r/silverbugs, Reddit's silver-collecting community. There is definitely a higher-than-usual concentration of Trump supporters there and even they were lambasting it for being a dumb thing to buy.
The thing is, these can't even legally be called "coins". A coin is only called that if it's made with sanction from the state. Privately-made coin-like objects are "rounds". Silver rounds are pretty common and are basically all worth melt value. I have no doubt these "commemorative coinsrounds" will meet their end five or ten years from now in someone's backyard kiln who will unceremoniously melt them down and cast them into some nice jewellery or a silver figurine.
Edit: I actually have some Trump design silver rounds. Not official Trump products, of course (or maybe they are, IDK). They are very common and worth nothing more than melt value. I paid melt value of these two. I traded one of them to my former roommate who's a Trump supporter for a cod.
Definitely going to keep the "never surrender" round that has his mugshot that they took after he surrendered though.
It's easy to test. There's a machine called a Sigma Pro that can test the purity of silver. It costs around a thousand dollars and every pawnbroker and coin dealer has one. If it isn't pure, they'll get busted immediately.
You can determine density using a scale, string, and some water, but this wouldn't be reliable enough to determine silver purity beyond 1-1½ significant figures. 950‰-970‰ pure silver would probably be within the margin of error you'd expect for 999‰ pure silver. That silver is basically "contaminated" from a dealer's perspective because it's unsellable due to being a strange purity and would have to be refined into 999 silver at a significant cost.
Dealers don't do this. A Sigma Pro machine is easier, more reliable, and faster.
For that reason, if you only had 1 ozt of it (or even 10 ozt), a dealer would maybe generously offer you half or two-thirds of melt value.