https://www.amazon.com.be/-/en/Groun.../dp/B07GVGBLBC
Type used in surveillance cameras. They call it "balun" due to mode of the transformer is built. But I dunno if it isolates high AC or DC superimposed***; it is made for isolating 2 grounded devices, only for breaking the ground loop (also, I suspect the transformer being bypassed fot HF).
***like for all those sets with bridge diode rectifier from mains.