The cheapest (and shortest) adapter cables are working fine too. I bought one of these:
Sadly those Chinese sellers often forget to write the polarity into the product description. But since center=positive is the more common case, most of those cables are wired like this.
Then again, there is a potential for issues if someone plugs it into a USB port that is not supplying the correct amperage, whether that be 0.5A, 1.2A, 2A or even 3A now with usb-c plugs.
It doesn’t matter, if the USB port provides a current higher than 1.2A, since the OSSC only draws as much power as it needs (which should be a little less than 1A… if i remember correctly). But it’s not recommended to use a USB port, which provides a current less than 1A. I don’t know for sure what would happen on a 0.5A USB port – but i would assume: in the best case the OSSC won’t turn on (or automatically turns off when drawing too much power)… in the worst case you could damage the voltage regulator of the USB port (very likely), your OSSC (more unlikely… i guess), or both.