Theoretically, I think a USB optical drive works just like a flash drive or external hard drive.

So, maybe get an adapter for your smartphone that converts from female USB A to whatever USB port your phone has (either USB C or MicroUSB or… some Apple proprietary thing). Then bring a disk and your phone and the adapter, connect it all up, and see if it’ll read the drive. (Probably worth testing with a flash drive beforehand to make sure your phone/adapter work as expected.)

Alternatively, some external optical drives will have an aux out. If you bring an audio CD, you could just bring some headphones with a regular 3.5mm audio connector, pop the CD in, plug in the headphones, and see if you get audio.

For either one, you’ll probably need to connect the drive to a 110V power port. I think most external optical drives would require that. Some, I think, instead get their power from dual USB plugs, so you might have to bring a battery-powered charger with a USB port as well.

Of course, depending whether you already have any of these things lying around your house, it might be more expensive to buy all the stuff you’d need to prove the drive works before purchase than to just purchase two or three hoping one works. Also, the people working at the thrift store might not take kindly to what you’re hoping to do.

That’s… kindof the cost of purchasing things (particularly electronics) at thrift stores. There’s not necessarily a good way to determine if it works before purchase.