I think it's a pity the Jolla doesn't support US 3G/LTE frequencies, even just for Europeans visiting the USA but I can't think of any reason why Jolla would want to be in the US market. It's totally unlike (no pun intended) Europe.

Everyone expects phones to be heavily subsidised and the contract tariffs are set up such that that is the only sensible way to buy a phone. We have call+data monthly rolling contracts in the UK for less than $10 a month now for people who bring their own devices.

Then you've got Apple who will run to the courts as soon as anyone enters the US with something that vaguely might look like one of their 'innovations' and ask for millions and an injunction.

You can see why a small European company would not bother with the USA.