Don't try these kind of gadgets on your smartphones. I used it by mistake on one of my samsung devices and the so called photostick made my phone completely stuck for a while. I mentioned a link from where I bought this device. Please keep an eye in future. These gagdets surely look and the main thing is price.
If I've found the same product you're talking about, (basically looks like a usb memory stick)
I'm not sure of the benefits of it.
Are you looking at saving internal storage ? Samsung's own usb C to usb A dongle is relatively cheap and would allow for a usb memory stick or micro sd to usb adapter to be used as an OTG option.
Or is this photostick used for something else that I've missed?
I searched a lot about this product named Photostick. It only transfer your photos from your smartphone to it's storage. You can do that with the help of memorycard. If you are wishing to learn more about Photostick Mobile for Android devices, I found an article on this - https://ixwallet.org/photostick-mobile-for-android/.
I bought one for myself and it isn't working. Tried several times contacting the company but no response. Don't get ripped!