I have no clue if there's indeed any proof for such a claim, but the theory that I read elsewhere is that it's a way to obfuscate money flows.
If a foreign nation (Russia, China, North Korea, whoever) would like to engage in the election, they can't just donate to the campaign officially. But instead, they could buy a couple thousands of these coins in smaller transactions.
TBH I'm rather with you. I think the majority of these coins is just bought by some MAGAs. For foreign nations there'd be probably more efficient ways to transfer money like shares etc.
You would be gravy, but it would be easy to shovel millions of oligarch money into his organization which will lose it by buying the oligarch’s overpriced services.