As it turned out, ordering those turntable belts from Germany wasn’t a tariff test, because the “less than $800” import rule was still in force for the EU at that time.
Now that I have acquired a vintage JVC VL-5 turntable, to compensate for stupidly letting go of the one I owned long ago, I’ll place another belt order with Thakker to see what happens. A little outfit like that losing its American customers would be a crippling, and perhaps fatal, blow.