You wrote for brand new one that it can be on either Sailfish OS or Android.
The thing is, I don’t remember Jolla shipped any with Android on it. So if it is unopened, it should be on Sailfish OS for sure.
Also, as I said, t hese are from the manufacturer that tried to sell them on open market after jolla could not pay for them, so they put android on them and tried to sell them as android tablets.
Just in case you’re curious, you can actually create an account on Tradera as a non-Swede, but on the account registration page, you first need to click on ‘Sverige’ in order to get a drop-down menu where you can select your own country. The personnummer is only needed for Swedish users.
You can also (first) click on ‘Språk’ to get a drop-down menu where you can select between a couple of different UI languages (including English).