Here is a USA link for the USB isolator
Searching for USB opto isolators brought up this, for $20: https://www.amazon.com/GeeekPi-Isolator-ADUM3160-Isolation-Protection/dp/B07QKYYCD8/
So there are options, at least. You'd have to do a bit more reading to confirm what exact protections it provides, and it only operates up to 12Mbps, so it's slow. But that may not be a problem.
I got one of these USB opto-isolators recently. It cleaned up the noise on my USB mixer board. No more digital switching noise. https://www.amazon.com/dp/B07QKYYCD8