The USB port is a serial device. You access it using the pyserial package. Here is a link to the documentation.
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Search for "python USB examples" or "pyserial examples" and you will get lots of stuff to help you. As to "unintentional electromagnetic emissions", if your device(s) is FCC Class A or B certified in the US or equivalent in other countries you should not need to worry about it. If not you will need external test/detection equipment.